Yes, we’ve had something similar happen a few times as well. In the end, we were able to navigate it without a professional mediator, and one of the leaders eventually stepped down and away from the project. But the experiences caused us to stop entering into agreements with two “co-directors”— we will still do either an agreement with a single project director or a committee, but not the “co-director” or co-lead model. I hope your situation can be worked through without too much strife for all involved!