this fixes Brynjolf. but not the other market members.

push Brynjolf to the ratway door (sprinting at him, takes a while)

talk to him, and whilst hes still conversing, enter the ratways.

He should be on the other side with you, now attack him, and run down to the ragged flagon.

once inside, he should follow, then yield, and talk to him

For all those on Xbox and PS3.

Save frequently!!