Message Storage taking up space but has no files to delete

I changed phone and restored a backup from iCloud. This new phone only has 64GB and my old had 128GB so when restoring it filled up and I had to delete my messages to help clear some space.

Messages are still taking up 36GB of space though, with 27GB in videos, even though I've deleted all the messages associated with them.

If I click on Videos (same for the other folders) they're all empty.

How do I remove these files if I can't see them?