Anytime I recruit a unit better than a levy or settler they die of attrition in my territory. The city they are sitting in produces more than enough to pay their maintenance but they wont take it for some reason.

I had same issue one game but I could use trained units just none that required equipment. I made a new game and it worked. I think it may be if you have a large number of barracks. i noticed one wasnt ever getting any weapons.

I've noticed that only my levies reliably got maintenance; as a result, I decided on having standing armies of levies and, when needed, mass-recruiting stronger armies. They'd fill their purpose (defeating ghuls or crushing enemy armies) before they died to attrition, and times of peace generally last long enough for more recruitable units to appear.

UPDATE: It looks as if building a warehouse lets spearmen get the gold they need (if they camp on the city and, of course, I have enough goods); presumably that'd work for other units as well.