need help with Accuracy/Mastery discrepency

[Drift]

So I am trying to fix a song here.  The bass line has 840 notes of which I hit 100% and the mastery with all difficulties (the song is DD) cranked up yet mastery shows 56.4%.  I was able to locate the line in the bass.json file with total notes.  So from here what line dictates the calculation of Mastery? 

 

 "Score_MaxNotes": 840.0,

 

 

 

[Alex360]

Please bump, I know It's old, but..
We calculate mastery as in official DLC's, but song difficulty values are still unknown, can I get more feedback\help on this?