Could it be the rubber in your 3D printed ball was too soft?
I’ve not had any issues with movement of the RAM clamped phone or GPS cradles over a 5000 mile trip through a lot of inclement weather, and countless shorter trips. I did need a spot of locktite for the ball that “screw-expand” fits into the inside of the bar end.
2017 Ducati SuperSport S
2015 Ducati Scrambler