I have a simple planetary gear mechanism that is driven by an Xpresso rig. I want to export it to SketchFab. Typically I export the file in the FBX format, and it usually works. In this rig, almost all the Xpresso relationships transferred satisfactorily, but one set did not (marked in yellow - attached). The source elements are splines, which I thought may have something to do with it, but that doesn’t hold up. For example, the Carrier B Rubedo Wheel doesn’t rotate, but a clone object that is parented to it does. So that makes no sense.
I can send you the model via Dropbox. It’s too big for posting.
BTW: I connected with James in tech support and he said the SketchFab exported for R20 is broken - hopes to have a new one out soon.