Hi,
I’ve tried using the leg_3jnt_01 with foot_bk_01. After i push the leg_C0_ik_ctl (ikSpring) and rotate the x axis about negetive 40 the jointEnd and the joint above that flip to -180. I tried this with leg_2jnt_01 nothing of this sort happens. Here is the maya file. Please look into it.
https://drive.google.com/file/d/14DgIXy7w8FkpAtOpMaCH3axZvBbCqNpa/view?usp=sharing
Thanks