Having a rifle or smg (non-SDAR weapon)in hand while going into water by exiting from a boat will render your character unable to move/swim around in the water. Only controls that are working are Z and X to ascend and descend. Character can not swim around on surface or underwater in any other direction than up or down.
This issue does not occur when walking into the water from the shore.
Play as an infantryman with any rifle but the SDAR.
Get into a boat and drive to non-shallow water.
Exit boat.
I have not tried with every boat in the game, only RHIB and armed combatboat.
Also I haven't tried exiting from a helicopter to see if same issue occurs that way.
When character jumps into water from boat he is still holding his rifle as if standing on land.
I experienced this issue while playing Wasteland V9 on Altis by Sa-Matra.
Not able to reproduce although I'm using Dev build EXE rev. 114607. Exiting in the middle of the ocean in a RHIB / Assault Boat works fine. It takes a second until the character is able to move due to having hopped out of the boat but otherwise I have no issues.