I laid off of MSFS 2020 for a short time but the longitude worked fine with the mod from Flightsim.to and working title g3000 7.6. But during my short absents came update 7 and the new longitude mod. Now I have the same problem as you and it is terrible. Not sure of the problem. Have deleted the plane and reinstalled it with no change. I think maybe update 7 broke the autopilot. I am running it on PC