Thank you so much for supplying all of that information! That helps narrow it down a lot if it's happening on the title screen.
Based on cursory research, it's possible it's an issue with the Godot engine camera, as there seem to be some issues with camera positions returning non-number coordinates but I'm more inclined to believe I've done something wrong so I'll keep looking into it.
Unfortunately I didn't get a pause working in time for the game jam, and it will be added to the next update.
I've been looking into the problem and I've finally run into the issue myself but I can't seem to trigger it consistently. For the next update, I'll include fullscreen/windowed mode options and hopefully one of those will fix the issue for you as I think it might have something to do with window size. It seems this is a Godot issue unfortunately so it might not be something I can fix though I'll try to provide workarounds if possible.
If the next update (1.2) doesn't fix it for you, I will rebuild the camera system for patch 1.3 and see if that fixes the issue. Thanks for your patience!
