incredibly frustrated with TA manager

[SymmetryOfImperfection]

I have been called into the TA manager's office 3 times in the past 3 months alone. I never had an issue my first year now it seems like the issues don't stop. If it isn't them saying I grade too easy (even though I strictly follow the rubric) it is that I'm not caught up with my grading. Now I am grading very critically and am completely caught up, they tell me to come in for yet another meeting. I am dreading what it could be. I just dunno what to do about this.