Open File Station and enter your Documentaries folder and drill down to the individual files in there.
Right click on a video file (I trust you have them named correctly), select Properties and make sure the owner of that file is your Admin User for the NAS.
If you need to change it, select your Admin User from the drop down menu and then click on Save.
Note: You should be logged into the NAS as your Admin User, especially when uploading files etc., if not, then your files may not be owned by the Admin User.
Go to Control Panel > Users & Groups and then select your Admin User. Click on Edit and on the Permissions tab, make sure PlexMediaServer has Read/Write permissions. Click on Save.
After doing the above, once again try running Scan Library Files in Plex.
Also, in Control Panel > Shared Folders, edit your Documentaries folder and on the General tab, disable the Recycle Bin and click on Save.
The Recycle Bin has been known to cause issues in Plex. This has nothing to do with your current issue, but worth taking care of while you are at it.
BTW, in Windows 10/11 hold down Shift + Windows key + S, that will open the Snipping Tool. You can then select to capture a small area of the screen or an entire window etc. on the small toolbar that appears (top center) of your screen.
Hold the left mouse button down and drag the mouse to capture an area of the screen, or click on a window toolbar to capture a window, depending on what you selected on the toolbar.
After capturing the screenshot, click in the reply window and hold down CTRL + V keys to paste the image into your reply window here.
