I can see the synced content in manage offline media tab. But when I try to play the file it just says can’t play this file. Started on android 11. I’m on pixel 4XL. Trued to search for the file using file explorer. But that data folder shows nothing now
No logs no chocolate 
You probably have something that deleted the files.
Or a nice Android 11 bug that lost permissions on update.
Logs shows no errors.
Where the file downloaded before updating to 11? Have you changed the download location in settings?
OK I know what the problem is. Its mx player. Can’t play the file suddenly. I haven’t changed any settings, but it just decided not to work. Downloaded VLC and played fine.
Are you using Mx player betas? maybe they do not properly support Android 11 yet and use hacks that no more works.
Nope. Use mx player pro. Then uninstall it and installed normal mx player and same thing. I’ll try the beta
Tried everything. Clearing data. Force stop. Uninstalling. On normal pro and beta apps. Same problem. But mx player seems to stream from my server just fine. Just playing synced items is the problem. I’m gonna stick to VLC for the moment until maybe more people are on android 11 and the problem is widespread. Or maybe it’s just my phone. Anyways, VLC is looking just as good. Thanks anyways
You may want to contact Mx support so they can fix the issue too 
Pretty sure they try to extract file path from uri and that does not work on Android 11. Not much I can do on Yatse side.
So after checking stats seems Android 11 is faster to deploy than previous versions.
Will add a workaround by serving the files via internal web server for it until they fix on their side.