Yup I think I figured out the bug. If GSX is being used, and the whole cargo loading process is not completed, or if GSX crashes mid-way, the A350 does not take the payload values and there is no way to override it. It happened to me now in a flight, wherein I was flying from RJAA to KLAX and GSX crashed during the cargo / boarding process. The whole cargo weight got completely ignored and did not add to the overall calculation.
@Miao Si I tried your work around, but that only resets the ZFW to standard 140T, without any cargo weight or additional weight. So, the aircraft thinks there is no cargo and assumes that weight. Thats why the error disappeared. But this leads to incorrect weight and doesnt not match with SimBrief. Fuel weight is added separately so this is not impacted.
May be another field of cargo weight could help resolve and override the bug.
I hope this helps the team @haza2 @iniBuilds