So I went looking for the corresponding folders and saw that all the .caf files were there. I thought that dragging the folder icons onto the loop browser might get Garageband to reindex and recognise them but it was just experimental.
That i s exactly how it is done.
But an empty loop browser does not necessarily mean, that GB does not recognize the loops. Have you checked all filters?
The Loop browser may look empty, unless you click and select a button that is not dimmed. Or all your buttons dimmed, when you select the JamPack 1?
You may have selected a project signature that simply has no loops - like 12/4; and set the scale neither major nor minor, also the "preference" setting "preferences > Loops > keyword browsing > Filter for more relevant results" will exclude most of the loops from being displayed. With the signature set to 4/4 and selecting "All Drums" you should see lenty of loops in JamPack 1:
I'd move the loops folder back to exactly where it has been installed and where you indexed it last. If clearing the filters does not bring them back, check the permissions on that folder. Are you signed in from an admin account?
Make sure the permissions on the loop folders and the loops are set, so that you have read access.
And if you dragged your loops several times to the loop browser you now may have duplicate loops.
I'd rebuild the loop index, and start over; see this document:
Rebuilding the Loop Index in GarageBand
Regards
Léonie