Thanks @ChuckPa I changed permissions OF the PlexMediaServer folder.
All my media is in separate shared folders.
Here is the email I got from Task Scheduler:
Task Scheduler has completed a scheduled task.
Task: FixPlexMediaServer owner
Start time: Thu, 29 May 2025 17:06:35 +0100
Stop time: Thu, 29 May 2025 17:10:53 +0100
Current status: 0 (Normal)
Standard output/error:
From DS918plus