Whenever I start up the game I get the black fullscreen issue and the game only runs normally in windowed mode, I have tried the solutions given in the FAQs and the only way I've gotten fullscreen to work is when the game is running in double speed and deleting the options.ini file just creates the black fullscreen issue again and again. Is there any way to fix this?
On the affiliated Discord you can find the current preview build in #co-op_buddies channel' description. v9915+ have a "borderless fullscreen" option (as an option in "fullscreen" in Video Settings), which should help with that.