After update: I cannot enter a turret or use one on any aircraft.

[Von_Fontlebottom]

Even if I switch to a gunner who is actively firing, I'll be kicked from the "occupied turret" state and my button (or T and shift+T) do nothing. I can mount the gunsights without a problem, but I cannot take control of the gun. 

Any suggestions? My controls are mapped correctly and the mappings have not changed in over a month. 

[Von_Fontlebottom]

And the issue has resolved itself, meaning it must be something on my end, but I do not know what changed.

[AndyJWest]

Did you restart your PC at some point? There can sometimes be weird effects if you run IL-2 GB immediately after patching it, without a restart.