I have played MANY games since 1.19 and the overlay updates and have never had a desync/invalid gamestate/critical gamestate error that occurred as a result of complete flag control. Perhaps it is an issue with the specific language version you are using? I think this specific issue you are having is tied directly to your version of the game.
I am using the english version of the game and u can ask a lot of guys, mapcontrol message triggers this bug.
Only in custom games, Pantheon games are not involved, and I think it only happens on cataract, all the other maps I played, I never had mapcontrol, what i can remember.
The greatest fun was that, I played a game with Frogboy 2 or 3 weeks ago, I told him that this bug will happen, if we take all the falgs, he didnt believe me, and what a suprise, the message triggered the bug!