Still the exact same issue. Changes to the theme revert to #000000 and the theme colors themselves don't change. I have attached a browser console log for Firefox.
In case these images aren't legible, here is a copy of the log. This records logging in to AGOL, going to Open Data, opening the site, changing the theme colors, clicking Apply, Save, and Preview.
"Handler function threw an exception: TypeError: this.transport is null
Stack: send@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/server/main.js:1429:5
NEA_addSecurityInfo@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/server/actors/webconsole.js:2168:5
NetworkResponseListener.prototype._getSecurityInfo<@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/shared/webconsole/network-monitor.js:508:5
exports.makeInfallible/<@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/shared/ThreadSafeDevToolsUtils.js:101:14
NetworkResponseListener.prototype.onStartRequest@resource://gre/modules/commonjs/toolkit/loader.js -> resource://devtools/shared/webconsole/network-monitor.js:457:5
Line: 1429, column: 5" ThreadSafeDevToolsUtils.js:80
Key event not available on some keyboard layouts: key=“c” modifiers=“accel,alt” browser.xul
Key event not available on some keyboard layouts: key=“r” modifiers=“accel,alt” browser.xul
Key event not available on some keyboard layouts: key=“i” modifiers=“accel,alt,shift” browser.xul
torii-provider-arcgis.fetch called... opendata-ui-db943b38a7eeac6b30e5ea00ee7ad9b9.js:29:27066
Password fields present on an insecure (http://) page. This is a security risk that allows user login credentials to be stolen.[Learn More] opendata.arcgis.com
Use of getAttributeNode() is deprecated. Use getAttribute() instead. init.js:197:418
cdn server url: //cdn.arcgis.com/cdn/20355 config.js:570:7
cdn server url: //cdn.arcgis.com/cdn/20355 config.js:570:7
The character encoding of a framed document was not declared. The document may appear different if viewed without the document framing it. postsignin.html
cdn server url: //cdn.arcgis.com/cdn/20355 config.js:570:7
Use of getAttributeNode() is deprecated. Use getAttribute() instead. dojo.js:219:64
cdn server url: //cdn.arcgis.com/cdn/20355 config.js:570:7
Use of getAttributeNode() is deprecated. Use getAttribute() instead. dojo.js:219:64
Firefox can’t establish a connection to the server at https://community.esri.com/socket?when=open&transport=sse&heartbeat=false&lastEventId=0&id=a2adcde6-298d-46a1-8dca-77b4459313a6&_=1481812743434. app.js:136:21184
torii-provider-arcgis.fetch called... opendata-admin-56ca48483eed766ce75e392857a543fe.js:30:9772
Use of getAttributeNode() is deprecated. Use getAttribute() instead. init.js:142:436
site-header::preview true vendor-f08c0bf949258f9fc373b1981b75dd14.js:42:21046
ember-intl: translation: 'components.od_search.label.find' on locale: 'en-us' was not found. opendata-admin-56ca48483eed766ce75e392857a543fe.js:32:1281
Loading mixed (insecure) display content “http://gis.baltometro.org/graphics/bmc-wheel-fb-white.png” on a secure page[Learn More] vendor-f08c0bf949258f9fc373b1981b75dd14.js:3:28515
Use of document.createAttribute() is deprecated. Use element.setAttribute() instead. vendor-f08c0bf949258f9fc373b1981b75dd14.js:33:977
Use of setAttributeNode() is deprecated. Use setAttribute() instead. vendor-f08c0bf949258f9fc373b1981b75dd14.js:33:1021
Loading mixed (insecure) display content “http://gis.baltometro.org/graphics/Thumbnail_Traffic_Count.png” on a secure page[Learn More] vendor-f08c0bf949258f9fc373b1981b75dd14.js:60:1821
Loading mixed (insecure) display content “http://gis.baltometro.org/graphics/Thumbnail_ACS0812_QuickFacts.png” on a secure page[Learn More] vendor-f08c0bf949258f9fc373b1981b75dd14.js:60:1821
Loading mixed (insecure) display content “http://gis.baltometro.org/graphics/Thumbnail_Building_Permits.png” on a secure page[Learn More] vendor-f08c0bf949258f9fc373b1981b75dd14.js:60:1821
Loading mixed (insecure) display content “http://gis.baltometro.org/graphics/Thumbnail_Max2040_StoryMap.png” on a secure page[Learn More] vendor-f08c0bf949258f9fc373b1981b75dd14.js:60:1821
Loading mixed (insecure) display content “http://gis.baltometro.org/graphics/Thumbnail_Traffic_Count.png” on a secure page[Learn More] vendor-f08c0bf949258f9fc373b1981b75dd14.js:33:1021
Loading mixed (insecure) display content “http://gis.baltometro.org/graphics/Thumbnail_ACS0812_QuickFacts.png” on a secure page[Learn More] vendor-f08c0bf949258f9fc373b1981b75dd14.js:33:1021
Loading mixed (insecure) display content “http://gis.baltometro.org/graphics/Thumbnail_Building_Permits.png” on a secure page[Learn More] vendor-f08c0bf949258f9fc373b1981b75dd14.js:33:1021
Loading mixed (insecure) display content “http://gis.baltometro.org/graphics/Thumbnail_Max2040_StoryMap.png” on a secure page[Learn More] vendor-f08c0bf949258f9fc373b1981b75dd14.js:33:1021
Loading mixed (insecure) display content “http://gis.baltometro.org/graphics/Thumbnail_Traffic_Count.png” on a secure page[Learn More] vendor-f08c0bf949258f9fc373b1981b75dd14.js:4:2169
Loading mixed (insecure) display content “http://gis.baltometro.org/graphics/Thumbnail_ACS0812_QuickFacts.png” on a secure page[Learn More] vendor-f08c0bf949258f9fc373b1981b75dd14.js:4:2169
Loading mixed (insecure) display content “http://gis.baltometro.org/graphics/Thumbnail_Building_Permits.png” on a secure page[Learn More] vendor-f08c0bf949258f9fc373b1981b75dd14.js:4:2169
Loading mixed (insecure) display content “http://gis.baltometro.org/graphics/Thumbnail_Max2040_StoryMap.png” on a secure page[Learn More] vendor-f08c0bf949258f9fc373b1981b75dd14.js:4:2169
Loading mixed (insecure) display content “http://gis.baltometro.org/graphics/traffic.jpg” on a secure page[Learn More] jquery.min.js:3:13325
Blocked loading mixed active content “http://prod-od-umbrella.s3-website-us-east-1.amazonaws.com/assets/fonts/glyphicons-halflings-regular-448c34a56d699c29117adc64c43affeb.woff2”[Learn More] edit
downloadable font: download failed (font-family: "Glyphicons Halflings" style:normal weight:normal stretch:normal src index:1): content blocked source: http://prod-od-umbrella.s3-website-us-east-1.amazonaws.com/assets/fonts/glyphicons-halflings-regular-448c34a56d699c29117adc64c43affeb.woff2 preview-css-b81ccb466c5ac8d5e49dac72ad807f1871e9a021.css:25:18769
Blocked loading mixed active content “http://prod-od-umbrella.s3-website-us-east-1.amazonaws.com/assets/fonts/glyphicons-halflings-regular-fa2772327f55d8198301fdb8bcfc8158.woff”[Learn More] edit
downloadable font: download failed (font-family: "Glyphicons Halflings" style:normal weight:normal stretch:normal src index:2): content blocked source: http://prod-od-umbrella.s3-website-us-east-1.amazonaws.com/assets/fonts/glyphicons-halflings-regular-fa2772327f55d8198301fdb8bcfc8158.woff preview-css-b81ccb466c5ac8d5e49dac72ad807f1871e9a021.css:25:18769
Blocked loading mixed active content “http://prod-od-umbrella.s3-website-us-east-1.amazonaws.com/assets/fonts/glyphicons-halflings-regular-e18bbf611f2a2e43afc071aa2f4e1512.ttf”[Learn More] edit
downloadable font: download failed (font-family: "Glyphicons Halflings" style:normal weight:normal stretch:normal src index:3): content blocked source: http://prod-od-umbrella.s3-website-us-east-1.amazonaws.com/assets/fonts/glyphicons-halflings-regular-e18bbf611f2a2e43afc071aa2f4e1512.ttf preview-css-b81ccb466c5ac8d5e49dac72ad807f1871e9a021.css:25:18769
TYPECLASS: site opendata-admin-56ca48483eed766ce75e392857a543fe.js:25:14999
ember-intl: translation: 'components.od_search.label.find' on locale: 'en-us' was not found. opendata-admin-56ca48483eed766ce75e392857a543fe.js:32:1281
torii-provider-arcgis.fetch called... opendata-ui-db943b38a7eeac6b30e5ea00ee7ad9b9.js:29:27066
site-header::preview undefined vendor-bb026dc6cd399f215b23c8102e55b33b.js:47:10800
Use of document.createAttribute() is deprecated. Use element.setAttribute() instead. vendor-bb026dc6cd399f215b23c8102e55b33b.js:33:1687
Use of setAttributeNode() is deprecated. Use setAttribute() instead. vendor-bb026dc6cd399f215b23c8102e55b33b.js:33:1731
Password fields present on an insecure (http://) page. This is a security risk that allows user login credentials to be stolen.[Learn More] data.bmc.opendata.arcgis.com
Use of getAttributeNode() is deprecated. Use getAttribute() instead. init.js:197:418