Rig dissapearing randomly in some tool functions

Hey, bit of a weird one. But I have made a number of animation tools in motionbuilder, and a few of them will sometimes cause the rig to collapse or disappear when run. One of them is using the pose system to store poses over a certain number of frames, and the other is just querying fcurves on the rig for a tween style tool.
The fix I have for it, is to reset the character to stance pose on a not used frame and them select all objects in the Ctrl rig and key in TR or body parts mode… Then the character comes back and I can set a key on one of the frames. Then going forward it seems to work fine.

However I can’t reproduce it reliably so it’s hard to figure out whats going wrong, but it happens enough to be annoying… So I wondered if anyone else had come across anything similar?