I ran into a problem trying to log into the Emby app on my new Lumia 950/XLs that I picked up in the recent bogo deal.
When I opened the app and entered Server details manually, the app got hung up on "Getting Server details...".
The emby server log showed the server was delivering "/mediabrowser/Users/Public?format=json" to the phone and that was the last request.
On the phone I went to "About" -> "Logs" -> "Send Logs".
In the Phone app log there was an entry that said it was unable to convert "Smart" into "MediaBrowser.Model.Configuration.SubtitlePlaybackMode".
When I went through the users list returned by the server, I found Smart, and the user it was connected associated with.
After I changed the affected users, the app started working.
While I did send this information to the developer, I wanted to update the community in case you encounter a similar experience while the developer updates the app.