Hopefully not a daft question, but the BB shell has been faced and it is definitely parallel?
For a PF BB not sure facing of the BB shell has any influence. More importantly is the diameter of the BB shell within spec, is it even round, and is it parallel and aligned with the other side? I suspect not because the way modern bikes are manufactured means BB’s are not manufactured very well at all meaning bearings are out of alignment relative to each other and angular forces imposed on the bearings that they are not designed to handle. Hambini may be a Dick of the highest order, but he’s definitely onto something about the shoddiness of all bottom brackets shells in frames at every price point…from the cheaper end to the high end boutique. They’ve all been measured and found to be shockingly out of alignment in many cases. If you can’t align your bearings accurately you have no hope.
Maybe look at a one piece insert BB shell form one of the several aftermarket companies that make them.