This won't help, but just curious as to which business structure you registered for MP under (eg individual, or company [trust, partnership etc])?

So far (and as far as I know) this has been happening to accounts that registered as trusts, partnerships etc, and I suspect it has to do with the fact that there are named partners of the business who are not ID verified, as they only provide the option to verify the account holder when you go through the registration process (again, as far as I know). Sometimes it trips the account up immediately, some accounts have been like yours - receiving payouts successfully for a while and then bang, the rug gets pulled. 

If you registered as an individual, though, then it would appear to be for a different reason, so I'm hoping that either the info above helps when communicating with eBay on the matter and determining how to resolve, or  if registered as an individual (and if it's feasible) you can post any updates that may help resolve similar situations if / when they occur to others. 

eBay do not seem to be well equipped to be handling these issues, unfortunately, I really hope they get their act together soon because this has been happening for far too long, to far too many people. 😕