When I try to open the Plex app in Windows 11 there is no response, no icon showed in the task bar and I found it appeared in the task manager when I started it but disappeared quickly. PMS works fine.
Here is the log, if it helps:
Feb 24, 2022 15:00:11.824 [8504] INFO - Starting Plex version: 1.40.1.2823-6f60f3a7
Feb 24, 2022 15:00:11.824 [8504] INFO - Running on: Windows 10 Version 2009 [10.0.22000] x86_64
Feb 24, 2022 15:00:11.824 [8504] INFO - Happy Plexing!
Feb 24, 2022 15:00:11.823 [11820] INFO - [OpenGL] Selected angle renderer.
Feb 24, 2022 15:00:11.823 [11820] INFO - [OpenGL] Default surface format version: 2.0
Feb 24, 2022 15:00:11.823 [11820] INFO - [OpenGL] Selecting surface format version: 3.0; profile: 1
Feb 24, 2022 15:00:11.920 [11820] INFO - [OpenGL] Testing surface format version: 3.0
Feb 24, 2022 15:00:11.921 [11820] INFO - [OpenGL] Setting default surface format
Feb 24, 2022 15:00:11.921 [11820] WARN - [OpenGL] Warning: Setting a new default format with a different version or profile after the global shared context is created may cause issues with context sharing.
Feb 24, 2022 15:00:11.921 [11820] INFO - [Settings] Web inspector port 0
Feb 24, 2022 15:00:11.939 [11820] INFO - [NanoServer] Starting nano server.
Feb 24, 2022 15:00:11.939 [11820] DEBUG - [NanoServer] Setting app support dir to C:/Users/22868/AppData/Local/Plex
Feb 24, 2022 15:00:11.941 [11820] INFO - [NanoServer] Found available port: 32700
Feb 24, 2022 15:00:11.941 [11820] INFO - [NanoServer] Changing nano server port from 0 to 32700.
Feb 24, 2022 15:00:11.941 [11820] DEBUG - [NanoServer] Setting listener port to 32700
Feb 24, 2022 15:00:11.941 [11820] DEBUG - [NanoServer] Setting environment up.
Plex Windows: Plex-1.40.1.2823-6f60f3a7-x86_64
PMS: 1.25.6.5577-c8bd13540-x86_64_DSM7 (Synology)
Windows Ver: Windows 11 21H2
OS Build: 22000.493