When I merge a larger number of chest, the graphic doesn't show anymore, only a sidewall and a transparant roof (you se the terrain). I can do any size X 5 but hen X 6 it goes wrong. F.e 6 x 6.
Don't know how to attach pictures here.
Using Factorio 17.79, MergingChest 2.2.2

When merging large areas (6x6 and more by default) it uses trashdump sprite instead. It looks like fenced off area. Would that be what you see?

Yes, that is it.
Sorry, missed that option (in my reading).
Working as intended,