I am not sure what is happening, but when I enable time on a layer and share it as a service, the resulting upload is dysfunctional as the attribute data for the time enabled layer is missing.
My time enabled point layer contains a total of 608 attributes for 32 sites (19 instances for each site). I shared this time enabled layer as a service on ArcGIS online, and when I checked out the new feature layer (hosted) online all 608 attributes are missing from the point layer and my points are missing from the map. I can open the attribute table and see the column titles though they are empty of data. The time slider is also present and even depicts the correct time frame though there is nothing to animate. I can share the same point layer with time disabled as a service, and the 608 attributes are present.
I should mention that when creating and adjusting the time enabled layer using ArcGIS Desktop, the time slider works perfectly and the data displays without issue. Prior to uploading the time enabled layer as a service, I made sure to correct all of the errors that were found (such as needing templates and having an in memory join).