Gun disapear

this happened to me in the old days of 2016 i remember that mg, dont remember the name of that mg, but has 35 round per shooting and 210 rounds in bag i get error when i change my bag 2 or 1 to play with it in sd as i remember, the solution's i did, that i resell that gun and problem was fixed, cause even when i remove it to my storage i keep get error so i discard that gun already and problem solved, or maybe send tickets to gm's