GarageBand won't let me open some files and says 'missing sounds' on iPad

My garage since the last 6 months doesn’t let me open some files as it says missing sounds.

I really don’t understand , because I have all the packs downloaded and I don’t use other files than the garage band packs…..

Another bad feature, is that the app doesn’t let you know which sound or pack is missing……totally frustrating.. I’ve used year ago, for example, REASON, and it showed me the exact file name that was missing…..

Never the less, I would like to know if someone has a solution, besides delete and reinstalling the app( which I don’t know if it will work)….

[Re-Titled by Moderator]

Original Title: iPad garage band missing sound?