I remember it mentioned somewhere in the forums, but couldn't find it in the bug section.
I was playing as MEC on Muttrah as machinegunner and was killed while using secondary sights. Upon my next respawn my mouse sensitivity went mad and I couldn't reduce it in the controls section because I was denied access to that section (it read something like "you cannot change your controls because your BUIS is on"). As I previously knew the solution would be to grab another BUIS kit and toggle it on-off again. But the point is that MEC has very limited amount of BUIS kits (only MGs AFAIK).
I was playing as MEC on Muttrah as machinegunner and was killed while using secondary sights. Upon my next respawn my mouse sensitivity went mad and I couldn't reduce it in the controls section because I was denied access to that section (it read something like "you cannot change your controls because your BUIS is on"). As I previously knew the solution would be to grab another BUIS kit and toggle it on-off again. But the point is that MEC has very limited amount of BUIS kits (only MGs AFAIK).