Hello necrosanto,
It sounds like you can see your jam packs in garageband but they are grayed out and unusable but they are there in your Apple Loops folder. I would recommend re indexing the loops, but depending on the version of Garageband you are using the steps may be different.
For the newest version of Garageband try this out:
Logic Pro X, GarageBand for Mac (v10.0): Reindex to fix issues with Apple Loops
http://support.apple.com/kb/HT5894
To reindex the Apple Loops library, click Loops at the top of the Loop Browser. Then, choose Reindex All Loops from the pop-up menu.
For earlier versions, try these steps:
Rebuilding the Loop Index in GarageBand 6 or earlier
http://support.apple.com/kb/ht2443
- Log in with an administrator account.
- If GarageBand is open, quit it.
- Click the Finder icon in the Dock.
- From the Go menu, choose Go to Folder.
- Type directory location: see this article.
- Click Go.
- Drag all "Search Index" files from the Apple Loops Index folder to the Trash. (These files will be rebuilt later.)
- Open GarageBand.
- Click the Loop Browser button. You may see the "No Apple Loops Found" message.
- Click the Finder icon in the Dock.
- From the Go menu, choose Go to Folder.
- Type the directory location: see this article.
- Click Go.
- Locate the Apple Loops folder and drag it from the Finder into the Loop Browser in GarageBand.
- Be sure to repeat steps 11-14, checking all the possible locations for loops, as described in this article.
The last step will reindex the Apple Loops folder. If you have installed the GarageBand Jam Pack, repeat the last step for the Apple Loops for GarageBand Jam Pack folder.
Thank you for using Apple Support Communities.
All the best,
Sterling