Have you edited your joystick/keyboard default.lua?
There was a typo that was fixed in 2.7 (cptligths became cptlights) however the hotas binding in clickabledata.lua still had a typo. (THROTTLE_EXTERIOR_LIGHTS was THROTTLE_EXTERIOR_LIGTHS).
I reported this when 2.7 fixed the cptlights and apparently it was fixed a patch or two back.
Run a repair and try using the stock bindings and see if that fixes your issue.