Civ acting odd...

[Ornen]

It says I can't build any iron-based units, but there's clearly a source iron two blocks west of the city. The iron is mined and connected to the city by a road, yet the game doesn't seem to register it as being there.

I'm currently at war with a couple nations, and there's some pillaging going on. It's not unlikely that another iron mine of mine has been destroyed, but I clearly have this one. What's going wrong?

 

[MrCynical]

My guess would be that you've traded iron to another civ at a time when you had multiple iron sources. All your sources except the one by your capital have now been pillaged, with the result that your only iron source is being traded to some other civ, so you have no iron supply for your own civ.

It's fairly easy to check and rectify this by checking what active deals you have, and terminating any where you're trading away iron.