Cannot copy and paste between projects anymore – GarageBand Review

Edit: I found out that this issue happened after I downloaded the “toy box” instrument sound pack. When I deleted it, the problem immediately went away. This is a very unusual bug. I used to be able to copy a track from one song, exit to the menu, then paste it into another song. I suddenly can’t do that anymore. Now I lost a track.
Review by An Angry Composer on GarageBand.