Possible Bug - Desktop Plex App for Win - Plex Setup Launches When Trying to Run the App

I had the same problem and so far I think the fix to my OTHER here fixed this behavior too:

The solution posted by moderator OttoKerner:

End all plex.exe processes.

then empty out the folder:
C:\Users<yourusername>\AppData\Local\Plex

So far so good on both issues since I emptied this folder and restarted the app.