Sorry you're dealing with all these issues, when I playtested it, none of these issues occurred. I wonder if it's maybe an fps issue or separate events clashing?
The only suggestion I can think of to probably fixing this bug during gameplay, would be If you can remember a map's layout and go to another map(or open the menu, scroll down, and use the "Return" function) This may fix the screen from being blacked out.
But again This shouldn't be happening. I'll try and see what could be the cause of this, I'm so so sorry for all the issues you've ran into! x.x
For the timed circle attack, yup! you're supposed to stop the circle as small as you can get it! Sorry if it wasn't clear I'll try to better communicate those next time!
If you find yourself stuck, the pre-saved files take place after each objective. (To save you have to scroll down in the menu, I know it's dumb, and ill try to rearrange the menu so the "save" option is visible!)
Thank you so much for this bit of feedback! I'll try cracking this case and patch this out as soon as I can!