We accept that (even if it's colloquial, at least it's some way to distinguish singular and plural 'you'), but it's absolutely never a starred option. But it seems we missed the 'most normal' option in one word order, so perhaps that's why you got it.
"You have/had been at work?" will now be accepted, as it should.
"Ya'll been at work" would not be accepted, it had to have either "have been" or "had been".