Got a weird bug on 3.7.5. I couldn’t reproduce it with a new session, for now it seems only the session I’m using for a game is haunted by it.
Symptoms:
A. deleting a sprite from a large metasprite creates garbage data:
Before deleting index “04”:

After:
(note the VHP432 stuff at the end; deleting more random sprites creates more of those from the bottom up)
B. duplicating a metasprite on the manager window messes with metasprites:
Before duplicating index “8” (notice “Signal” on index “10” has 4 sprites):

After:

… and the Signal metasprite became filled with those VHP432 sprites at the end:

I thought it was just a bug caused by a metasprite having more than 8 sprites, but it didn’t seem to happen on an empty session (but I didn’t try too hard, I confess)