This is very good case in general, but I have two issues only with it - edges on the cuts of the side walls are too sharp - there should be chamfer or fillet. And the back is so thick, that wireless charging in my car is not working.
Is there a chance you could share the model file so I can rework these issues?
I would make sure your build plate is clean, I use IPA to keep my plate clean.
Your printer may also need calibrated,
I’m saying this because I have had no problems printing this on my printer, I use a P1S.