That's very possible I was watching a sorta documentary on the Bradley not to long ago and there was discussion about them removing some TOW Missile components when the upgraded the armor and turret controls which in addition gave them more crew and personell space also took away the Bradley's ability to float due a large increase in weight not that I ever truely trusted it's boating capabilities.

The Marines have tracks (armored personell carriers) and LARv  light armored reconnaissance vehicles both of which are meant to be amphibious and both of which I have seen be successful and tragically very unsuccessful.

When they lunch those vehicles from the well deck of an LHD they plung down into the water and bob back up like a cork, they have this fine line of how deep they can plung into the water before the buoyancy of the vehicle is over come by its own weight and the water and then it sinks like a stone, it is from experience a very nerve racking sensation kinda like that first drop on a roller coaster