Support for multiple accounts in drive is pretty great (minor papercuts here and there) as long as all but one of your accounts is an Apps account. This feels like an issue that they've fixed but not rolled out.

Except this has been a problem for years, and according to a friend of mine who's had a "personal" Apps account from back when it was free, never has been a problem for Apps users, so I'm not sure what's going on on their end.