Pretty much, whenever you sneak in third person, the player model bugs out a little bit.
What I expected to happen was that the player model sneaking would appear as normal. What actually happened is that the player model did sneak correctly, but the armour remained static as if the player wasn't, and sank into the ground a little bit coordinating with the position of the player's head.
Steps to Reproduce:
1. Enter third person facing front, or back, by pressing F5.
2. Press shift to sneak.