hello!
I’ve asked this over on the answerhub at first, but never received a reply, so I thought I’ll try here; maybe one of you fine people can help me out 
I rigged a character with the Animation/Rigging Toolkit but for some reason some of the orient constraints in the anim rig have rotation values baked in.
so when I switch from FK to IK and vice versa weird stuff if happening.
stuff like this
this happens in quite a few places, the wrists, the ankles, the shoulder.
I haven’t been able to figure out how to fix it;
I changed some settings in the IK constraints like interpolation type, but that didn’t help.
I tried rebuilding the rig again from all the way back at ‘skeleton placement’ but that didnt work either.
any idea how I could go about fixing this rotation issue? 
here’s another screenshot just to illustrate. look at how the rotation values of the wrist change
any ideas would be much appreciated.