Co-Founder Equity Split - 409A valuation for option grants

Using a throwaway bc my boss knows my main. I'm dealing with a situation and need some guidance.

409A valuation for option grants. I've been dealing with this for about 7 weeks now and the situation isn't improving.

I have already tried to resolve this directly but the other party is not cooperating.

Has anyone been through something similar? What worked for you?

I went through almost the exact same thing.

What worked for me was having everything documented. It took 3-6 months but was worth it sadly.