I have two of these plates, and noticed recently that one of them wobbles on top of both my Sachtler 18 and my separate "Sachtler Sandwich Touch & Go Adapter." Both plates used to work just fine. One still does. The tripod is more wobbly than the separate adapter.
Clue #1: On VERY close examination, I can see that one of them has sharper edges than the other. The other one has an additional bevel between the slanty surface and the bottom (wider) plane. The sharper one is the plate that wobbles.
Clue #2: I recently used mounting screws that protruded slightly. I wonder whether that affected the receiver on the top of the tripod. But it shouldn't have affected the Sandwich.
Has anybody had problems with these very expensive plates? At $85 apiece, they shouldn't be problematic.