I am having the same issue here. I have a Project that I am trying to Video Mixdown. (1hr 47min)
Rendering to a LanShare Unity Drive so no question about Drive Format. I have routinely done large mixdowns like this before with no issue. There is plenty of drive space available.
I have already gone through and Rendered all the effects.
Mixing to OMFI 2:1
Any further thoughts and discussion may be helpful. Thank you
Avid Adrenaline
Media Composer 2.7.7