Hi,
I've the same problem with my MDX D300 but only in use with Sigma 8-16. I've noticed that the tolerance of the rear buttons; especially view and trash, is very very little.
In opposite the Sea&Sea plastic rail camera - housing lock system present a wide tolerance. So we must be very carefully mounting the camera in the housing.
It's frustranting but I suggest to do a lot of locking tests before jump in the water
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