when restoring a set of blocks from a backup, it simply fills that area mostly with air, with some blocks leftover, like random sections of andesite or stone.

command I ran:
/bm restore blocks -60 0 137 -84 30 91 2020/1/12-24:45:49
I tried using different backups, all to the same effect.
Does anybody know whats happening here?

Does it give you any errors when you run the command? You should also upload the log.