I've had this problem with F-Max screws. It stems from the fact that some manufacturers put a larger hex in the head than the accepted standard - in the 4-40 F-Mac screws (usually 1/16th hex) they put a 2.5mm hex. That makes the screws easier to turn, and makes the hex last longer (Ti is relatively soft) but it means there is much less material where the hex, the taper and the screw thread meet - and they snap.
Ti is much more ductile than steel or ally, so it should take shock and constant bending loads more successfully. However, shear loads are another matter! It's not the material that's at fault, it's the design of the screw.
There's a saying I first heard from Keith Bontrager, mountain bike pioneer. It goes
Strong, light, cheap - pick two.
Which two were those screws, I wonder!!
