In both Android and Windows 10, I'm unable to add photo attachments (from camera or from file) when using an offline map that was loaded from Portal 10.4. However, I am able to save attachments while the tablet is online. To make it more confusing, I loaded the same map onto to AGOL and had no problems with adding attachments while offline. So it seems the problem may be with the configuration in Portal? It's using ArcSDE and Microsoft SQL Server. I'm using relationships classes, editor tracking, and domains, but the tables are pretty simple otherwise. Any suggestions? I don't see any settings I can change in the Portal pages, so is there something I can look for in the ArcGIS server settings?
10.3.7 build 1018
The message "Unable to update feature" flashes briefly on the screen, then the message "Posting attachment" stays on the screen until I force close Collector.
"Attachment failed to upload"
"One attachment failed to upload."
However, the app doesn't lock up like in Android.
I found this similar thread from 2015 that hasn't been resolved: