Might need to contact MPA, sounds like one or the other is a tiny bit out of spec. I only takes a tiny bit in these dovetail systems and they simply won't hold. JP had problems with their prototype chassis slipping and evidently all it took was getting the amount they compensate for paint -vs- anodizing wrong.
This is IMO why the Arca/RRS/dovetail rail system(s) are problematic, it only takes a tiny bit out of spec across the manufacturers and even within the same manufacturer and things slip when loaded. I've seen bipods fall off at shoots after the user had not noticed them slipping during the day. Dovetail provides quick adjustment and a fairly non-obtrusive (compared to a full length pic rail) that allows full forearm use, but it's prone to slippage. Someone really needs to make a new combination something like a dovetail rail with shallow spaced scallops so you get the advantage of full adjustment, but the solid lockup or more than just a wedge.
Also none of these "knob" dovetail QR work well, RRS had to change their knurled knob on their bipod plate because people could not get them tight enough to stay and IMO even the new knob is a poor bandaid. What they really need to use on these things is the camming style QR used in mountain biking wheels/seats, some clamp tight enough you can snap the steel bolt.
Low profile short QR levers will never provide as tight of a lockup as hex bolts/nuts will, knurled knobs are even worse. It's the reason Geissele will not make a quick release optic mount.
