The collapsing could be a result of the pole targets.
when you switch them on and off the angles apparently change in the newer version of rigify. This leads to the shoulder closing in.
The head spinning is the bug I cannot spot as of yet. I have been deleting the rig head bone before import to get viable animations out.
All of this is apparently only happening when using unreal animations or pasting frames from an unreal animation.
manually animating a rig has no issues.
leaving me even more clueless as to what may be causing the head to spin.