I bet you never wish you got involved with this case!!
No problem, Stuart, I just wish I could take over your display and keyboard for a while 😝
Quit GarageBand. And if your MacOS version is later than 10.7. log off and log on again. Otherwise you cannot be sure, that garageBand really quits. Ehat is your MacOS X version, btw.?
Are you looking at the correct library?
The current GarageBand Version stores the Apple Loops in /Library/Audio/Apple Loops
To open this folder use the Finder's "GO" > Go to Folder menu, like this: Type
/Library/Audio
into the text field. Press the "Go" button.

Delete all folders with "Apple Loops" in the name and empty the trash, before launching GarageBand again.
Previous versions of GB also had "Apple Loops" folders in /Library/Application Support/GarageBand
Search this folders for loops as well.
Regards
Léonie