There are such strange things, but it works for me.
First of all, you should add a “pelvis” bone to your root chain (root + pelvis). After that, you can see incorrect vertical offset, don’t worry about it, we will fix it in the next step. The second thing is to add single pelvis chain with “Global Scaled” mode set (like the root chain).
After the above steps, we can fix the vertical offset using the offset of the root bone in the character’s pose(!).
