I have 812 mastery shown on the sim here:
https://www.askmrrobot.com/wow/simulator/report/be8c8165bbf64cd5b8bb7604e59358e9
But in game (with elegy) I have 927 which is 115 more than the sim, the amount that elegy gives. I also don’t see the So’Leah trinket adding any stats in the sim