That bug appears from 5.10.0 version of android app. Cast from web happens without any problem. Please fix that.
Are you really using 5.10.0? That is a really old version. Please update to the latest and see if you still have the same issue.
I use 5.9.X because this version correct casting to chromecast, all newest version has this bug (((
I’ll need the log from the latest version. There have been a lot of changes since 5.9 so if there is a problem, it might not be the same problem. I can only diagnose problems with the latest version of the app so I can test and find the cause.
Edit - To be clear, if it works from Web, then it should work from Android. When casting it does use the casting device’s profile to determine what it can or cannot direct play.