Cannot File Because Schedule K-1 Box 16 has code M but no code F

Hi! I was trying to e-file my tax, but encountered the below error. It's saying I have code M in box 16 on schedule K-1, so I also need to enter code F. But on my K-1, I only see B, C, M and AA in my box 16. What should I do? Shall I enter a code F with the amount 0?

 

Btw I have a code W in box 13 (legal and professional fees) with exact amount as box 16 code M... Not sure whether this is what makes things weird.

 

Thank you!! IMG32046.png