Hi,
I experience the same issue. Bought the A350 2 days ago, but on two seperate flights I had this issue. Latest was RCTP -> EDDF, aircraft was almost topped off with 92.000kgs in line with SimBrief's calculation (should be sufficient indeed), EFOB displayed -36.000kgs! Not sure whats going on here, or what I might be doing wrong.
I verified the weights couple of times of course.
Thanks in advance if anyone can help.
Best regards,
Marcel