To the original poster- I take it that you have re-set the pressure plate to 220/135 and aren't just using the 120 setting? If so then it seems to me that the film isn't lying correctly and thats probably because the adapter isn't seating quite right.
Frankly I don't know why Mamiya - or users- bother with this faffy and inconvenient adapter. Mine went back after a week when it kept causing the back of the camera to spring open mid-roll ( which has never ever happened with 120/220). You get no compositional advantage and lose the ability to switch from 67 to panoramic on a frame by frame basis. I can get 18 -in fact 20- panoramics on a roll by using 220 film and by using roll-film I'm not limited to 24mm max height.