Missing edge zone + volume mesh stuck
 

I'm having some weird behaviour trying to mesh a full FSAE car. For one, my domain is split, and the edge zone along one of the split lines is missing. It therefore won't mesh straight. Why is this? I'm importing from a .tgf:

https://puu.sh/JYU1Q/bfcf6a8d1d.png
https://puu.sh/JYXFP/38bcfd746e.png


Secondly, I tried meshing it anyway, and the volume mesh won't generate. It is stuck at 81%, 'processing poly improvements (collapsed)' with the console saying it's merging short faces/edges. I've tried 3 times, even halving the cells, and it runs for over a day not doing anything. What is going on? The surface mesh is perfect, I've never had this problem in a half-car symmetry simulation. How can I even diagnose this?:

https://puu.sh/JYZ9C/efcf20fe00.png