It's really weird that it works through ScummVM and not natively, but thanks for the tip!
Hi Laura, I wasn't the original commenter, but I think the reason is ScummVM bypasses the aging Allegro library. This will probably be fixed in AGS 3.6 since that replaces Allegro with SDL2.
That makes sense. Really looking forward to AGS 3.6 being a bit more stable and being able to leave Allegro behind.