I have similar problem with compiling complex level during "checking midpoints". It throws c++ runtime exception. I sent my level to Conitec support and they replied that issue will be solved in new release.
Because you have very specific problem, you must solve it with 3DGS support. I think the problem is in map compiler like in my level.
Support for free version is not available, you can see Game studio shop. There is introduced that
Quote:
Monthly tickets for email support are separately available at the online shop.
At online shop there is section "Gamestudio Artwork, Tools and Services", where you can buy "Gamestudio support ticket". But I don't know whether this is for free version users...