Caused by rB9a7f5f1bb422.
If using Auto IK (or targetless IK and Auto IK together), two temporary
constraints were added.
- from pose_grab_with_ik_add (Auto IK checkbox)
- from add_pose_transdata
Since both both do similar things, but cannot work in tandem (with
possibly different chainlengths for example), we have to decide which
type to prefer over the other (as in: do not create a constraint for the
It seems better to ignore the 'Auto IK' option on bones that already
have targetless IK set up for them specificallly [e.g. defining special
chainlength]. This way you can still work with 'Auto IK' ON generally
[with interactive chainlength control], but also have specific bones that
need their own custom chainlength.