I am not sure if this is the correct category for it. If not, maybe someone can change the category to the correct one.
I must add I have only tried this with the BLUFOR Sniper unit, but it could be it affects all other Sniper units as well. This issue for me occured when I tried it in the editor and when I played MP.
Basically what happens is that once you add removeAllWeapons this; to the init field of the Sniper unit and go prone you can not move forward and left at the same time anymore. The unit starts the movement but it just won't move. It looks like it's frozen on the spot.