Decided to try out the mixing graphic sets (though I don't plan to use this in any of my packs).
I opened one of GigaLem's levels, then changed graphic set. Most of the objects such as pick-up skills and the single-use dagger trap disappear, as seen in the pictures below. Also, the locked exit in the first picture seems to changed to an unlock exit in the second picture.
Shouldn't all objects remain intact when changing graphic sets?
They should indeed remain.
The changing display of the locked exit; it's probably still the locked exit, just displaying the open frame instead of the locked one.
Found the cause of this and fixed it. Uploaded a new experimental with the fix.