The issue when moving from 1 OS to another are the file paths. PMS stores the location of your media in an internal database using the file path for the OS. When you move to another OS, you can’t always reuse the same path so now everything gets unlinked.
The fix is to manually edit the database and change the paths. Otherwise you’ll have to recreate the libraries.
Read the while thread, but the steps in this specific comment are what you need to do. [HowTo] Plex database modification - Moving media the right/wrong way
