The filter cap bypass valve is in the center tube. The valve should open if the pressure exceeded a threshold (possibly around 20-25 psi??). Also, there should not be that much back pressure from the new filter element.
Could the center tube have come off and put back incorrectly any point in time (not necessarily the last oil change). Could the aftermarket cap have failed? Could the self regulating oil pump be creating too much pressure even for the relief valve? I do not know.
It makes me want to use ONLY a genuine filter cap if I ever needed one. Not even a Rein or Uro. And many of us change our own oil for a reason.
Anyway, here is where the bypass valve is and how it operates, explained well in this thread:
https://f80.bimmerpost.com/forums/sh....php?t=1809259
