Hi RG
Your photo doesn't seem to have downloaded so it's difficult to comment further. However, having looked more closely at your original photo, are we looking at an infill over the large rectangular surface? If that is so then perhaps you should try to reduce your infill density and see what happens. Also, what is the underside of the first layer like when you remove it from the bed? Maybe you have an adhesion problem.
I wanted to try blue painters tape but I haven't been able to find any stockists here in the UK although it seems to be advertised everywhere in the USA. I tried so