Flex Spline teeth skip under load. same results occur no matter the tooth profile, although I am using default tooth profiles from Fusion 360 addins, not sure if this will be an issue. Either way I believe the problem lies in the material of the FlexSpline (TPU)

I am using TPU in the first place to avoid the large flexure area needed if stiffer materials are used. TPU is super flexable, but maybe so flexable that the teeth are flexing as they are forced into the Circular Spline

I will be creating the next version. this time with a PLA FlexSpline to test more rigid materials. If this is successful the final design will not use PLA as it is too brittle for my liking.