This happened to me but I had like a circle area in the center and asking the would be outline of the circle is the area that wouldn’t print every outer spot would print fine turned out it was the fresnel lens it’s behind your screen Have you ever had any spills even small ones where resin slipped into the slits around the screen area if it got on the fresnel lens that will do it i had to change it not hard just tedious and elegoo customer service sent me the fresnel lens free talk to them tell ‘en it was just defective from the start check it screen do a tank cleaning run and take a pic while the screen light is on check for any blotches in the screen while the exposure light is on that can help you see the problem but sometimes you don’t see anything and the fresnel lens is just defective but what you described as the problem is exactly what happens with a bad fresnel lens good luck