I am having a similar problem, but I am shocked that it not many people are as well. This is the link to the post I made about 8 hours after yours.
What are you playing the media on? I am using Google Chromecast with Google TV
In my case, I believe the issue deals with audio as in suddenly I can’t play any AC3 or DTS files. However, I can play AAC files, which is what I have been mostly using Plex for the past couple of months. So I didn’t notice the issue until 2 days ago. I hadn’t updated the server software before I noticed, but I have now, but still no change. So not sure if the culprit is one of the server updates or the Google TV app. I haven’t changed any settings or hardware for a long time so it has to be software related. All I know is this is a mess and nobody else seems to be complaining about it.
