[=Skylonxe;488573]
Here is 4.11 issue with character mesh: Character mesh offset after calling crouch/uncrouch - Rendering - Epic Developer Community Forums
I had the same issue, but I also had made my own crouching code (that was very similar to the <4.10 implementations). What seems to have fixed it (if I remember right) was using GetMesh().SetRelativeLocation(NewLocation) instead of GetMesh().RelativeLocation.z = NewZ when correcting the Z of the CharacterMesh.
Don’t know if it’s intentional or a Bug.