Then I'm confused as to what the issue may be then. Very strange. As long as you are not restoring anything from backup until after you've tested your Google Play account, then I have no answer to your issue. I feel bad that we can't help you any further. It's just weird and I've never heard nor seen this happen before, at least not where it was unsolvable, but at this point, I have no earthly idea what is going and why it only works for you under stock but not custom ROMs.