Ever since I switched to 0.23.5 during ascent, my Kerbals invariably die at 14,000 Meters. The only mods I'm using are [0.22.x]Soviet Pack 2,0,0 and [0.23.5] MechJeb 2.2. The ship doesn't explode or anything like that. I'll just be going through the liftoff as usual and every time at exactly 14,000 Meters, the icon for my Kerbal in the lower right of the screen just disappears. The ship itself remains fully intact and still functions, but I obviously can't do any EVAs or anything that requires a Kerbal. This problem happens no matter what ship design I use, even if I use a stock ship. I poked around the forums a bit and could only find one other thread about this, which went unresolved. The general consensus was that the Deadly reentry mod was the only thing that could cause this, but I've never used that particular mod before.