Sorry, the version I placed in the previous message was the web player version. As of PMS version 1.20.3.3421-54b6523bd it worked for me. Yesterday removed/re-added the DVR to setup the new EPG support for my country. Currently I’m also on the same version as you and no issues there for me.
Try installing the latest WinTV (this also includes the latest drivers):
Yes, the tuner works on a different pc. I also managed to get the tuner working in another docker container. For me the problem seems to be the plex docker.
I created a new topic: