I just got the same error message and have no idea why. I'm new to Apple development, I barely even use Mac so it's not like I should have historical/clashing account issues. The rejection and error message is so useless I'm genuinely stunned it was allowed to be like this. To be simply told, "Your enrolment could not be completed" without ANY other info, no links, no advice, nothing? No wonder Apple is a sinking ship. Seems to just be sat milking as much as possible off the iPhone i-Everything hype and the growing Chinese market. Nothing at all is done with actual developers in mind. All form over function, leading to absurd rejection error messages like this. And then they ask that we pay $99 per YEAR for the privilege of all this nonsense.