Mega City Economy Problem

I have a modded Megacity (around 300k) whose economy imploded and I can't figure out what I am doing wrong.

Everything was humming along nicely - traffic flows around 70% average, I have a robust and flowing rail network, and everything is laid out with decent proximity to other zones.

I am importing 3,500, ore exclusively. I am exporting 29,300 split pretty equally across oil, ore, ag and forestry. I am not importing or exporting goods. I am seeing generic district industries pile goods up and abandon while commercial districts say they have no goods and abandon. What am I doing wrong?!

Edit: My unemployment rate is crazy high, like 20% and I can't get any zones to develop. Usually I build a bunch of offices and that helps, but they aren't developing right now.