Here is a forum thread on the Jellyfin forums from 2 days ago with an explanation and a solution. Looks like somehow the Roku Jellyfin client somehow has been marked as Beta which requires some extra steps for installation.

Could not have said it better!

I am not sure what the general expectation was from the mass influx of people coming from Reddit, I can say it saddens me to see the daily barrage of complaints. Lately it is not even constructive criticism, it’s just all out bitching about this or that…

Lemmy is ALPHA software, and suffering from a HUGE influx of new users. There are and will be growing pains.

Jerboa is ALPHA software, and suffering from a HUGE influx of new users. There are and will be growing pains.

Either get involved with development, move on to something else, or deal with it. Posting a daily rant (most of which have already been stated, and addressed or will be) is helping absolutely no one.