Wow Thank you so much for you`re feedback im glad you liked it.
And its not a bug its a feature.
Jokes aside. Since a donut has a hole in it the enemys can fly through this hole and dont get hit. Thats a mechanic i came up with when i was brainstorming. I tried to make a tutorial to explain this but unfortunatly i ran out of time so i couldnt finish it. Its stated in the Description however.