Into the zip file attached to this thread, there is a very simple mission that reproduce the bug. A screenshot is also in the archive that show the diver in complete freeze of animation.
Reproduce
1. Open ArmA 3 Mission Editor.
2. Add B_diver_F unit into water.
3. In the NAME field of the unit set A.
4. In the INIT field of the unit set: _dummy = execVM "test.sqf";
5. Create a test.sqf file and add: removeallweapons A;
6. Set the diver as Player and run Preview.
7. Your player is in complete freeze from moving.