Hey! I’m necro’ing this thread because I’ve just run into this in 4.0.9
I’ve found that if the IK/FK Blend is set to FK by default, it will also set the UpV control to default in the wrong position (next to the middle joint). As a result, the elbows/knees will flip with any IK movement including foot-rolls unless the UpV is manually set back to 0,0,0.
That also means “Reset” or “Reset all below” will return it back to the offset position instead of zero values.