I don't know what you mean by broken but I just tested it and it seems to work fine, I put x = 5 in the creation code of an instance, and show_message(string(x)); inside its step event and it displayed the proper value.
Also, back on topic, this issue has nothing to do with graphics, it is a bug in the window code, I have also tested and can confirm it is not related to room switching, simply during startup of the game, probably because game settings are being initialized before something crucial.
I have submitted a bug report.
https://github.com/enigma-dev/enigma-dev/issues/742