Metahuman Snail-like Neck

Hi All,

I’m encountering neck issue when retargeting my metahuman to FAB anim packs and depending on the anims, my jaw submerged into the neck during certain action like kicking, and have a snail-like shape (refer to attached) during idle on certain anim pack.

What is the probable root cause and how to fix this?

Thanks in advance.

JK