Did Plex end support of MKV or Web browser based playback?

Plex Media Server
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1

Server Version#: latest version of Plex on Unraid 6.12.8 via Docker
Player Version#: Opera 108 (Chromium based)

I have been watching Plex via my Opera browser for years. I installed the latest update to Plex Media Server today 3/14/24 and afterwords I can no longer play any MKV files via the browser. 90%+ of my library are MKV files. Playback in Plex client works file, but the way it buffers shows that it is direct playing the file and my PC is supplying the codec for the mkv file.

Did Plex end support of MKV or Web browser based playback? Is this a bug or is something on my server broken?

Possibly related, but Plex metadata server also stopped working for me after the update. I refuses to find any movie from any metadata source.

2

And just like that for no reason, playback of MKV files via my browser just started working again today. Still can’t get the metadata to work, but that is another issue it would seem.

3

After the upgrade I am experiencing the same issue on any browser, MKV movies stopped working.