So I was dogfighting this Fishbed one time and after I killed him, I ran out of fuel before I could RTB. So I decided to land on ground and extended my gears and flaps using the emergency gear and flaps knob, which worked.
After I quit the mission and entered another mission, my gears and flaps were permanently extended and I couldn't retract them back using the cockpit levels and buttons nor the keybinding. I tried both air spawn and cold start but they were permanently extended. I also tried multiplayer but this problem still persisted.