Our hosted data is missing on our open data site. The available raster downloads and story maps appear unaffected by the problem. I can query the REST services and an external website which share the same data sources is displaying the data content. Site location: http://data.burnaby.ca/
Sorry if my questions are a bit basic, but a lot of times something simple can get overlooked - is everything https? There were some fairly recent security requirements that may be gettting you - particularly if you have mixed #http and https environment.
One thing I see is a different behavior between IE, FireFox and Chrome - only IE shows your data icons.
If instead of http, as in the link you posted, I preface your URL with https, then I can see the icons in all three browsers. May be unrelated issue, but does indicate there might be something going on with security.
Using the https vs the http is a valid comment and worth the change, we experienced issues with the icons in the past. Our internal security has been a bumpy road lately so looking at our security policies may well be worthwhile.One of our team put in a request with ESRI support and it was indicated that a recent upgrade to the ArcGIS Hub may be related to the problem. Other sites have had problems similar to us since the upgrade which may require changes by ESRI. Thanks for giving our site a test your comments have been helpful.
ESRI support has associated the problem to a known bug: BUG-000120862