Gamemode construction script doesnt execute after level opening

Hello. Have very annoying bug with gamemode construction script.

First i meet it with defaul level gamemode. When game opens back default-maps , gamemode construction script doesnt fire at all.
I try to solve this problem, but came to opinion what default-maps gamemode never destroy and forget about it.

Now i meet same again, but not with default gamemode and not in default map.
Same behavior in PIE, SA and builded. Variables whos initializing in construction script - uninitialized.
But GM Begin play - fires!

So WTF is this? How to fix this?

Ok. I found how to fix it in PIE and SA.

Changing map defaults gamemode to any and back - fix it.

But problem still in build. And after the build, it comes back to PIE and SA.