Animation Editor: Missing Rootpart in 3.1

[MisterObvious]

Using the old animation plugin I am able to select all of this complicated rig's rootparts.
But when using the new 3.1 animation editor, the rig tree constantly ends right before the last selectable rootpart. (second picture)

This started happening since 3.1. It's a bug and I don't have workaround fix for it