This is rly old bug. Is over 3 years. Every time when reloging to account, vehicles weapons loadout reseting. Most on Sunderer, Lightning, Prowler main gun, Mosquito when u pick M18 Rotary, Liberator nose gun. This is rly annoying. Fix it, pls.
Provide as much detail as possible, including steps to reproduce the bug. You can never post too much detail. If you encountered this bug so many times, maybe you already know what series of actions is needed to produce it. I don't have this bug, but I got it coincidentally on PTS on NC character with Warden. Just a guess out of the blue, do you use ALT+F4 or another ways to forcefully close your game?
Does it happen on all characters (including new ones)? Did you try to create new account or play on another computer? Did your weapons become bugged simultaneously? It's not reproduction steps.
Just curious, but is your zoom for your Rotary actually purchased correctly? I ask because many years ago, they made changes to vehicle optics and everyone's certs were refunded. However, while players were required to repurchase their desired optics, there is still a bug where players' previously purchased zoom optics are still attached to their weapon of choice. Every time you relog, the game will automatically reset your vehicle to its default weapon until you properly repurchase the optic.
Did you take them off in VR Training? Do your loadouts reset in VR Training and Koltyr? Are you sure that you don't remember when it's happened? And you didn't answer, did your weapons become bugged simultaneously?
