Not sure I have seen this bug before? I'm playing as Rome and I'm desperately trying to upgrade my warriors to Legions obviously. I have at least 3 iron mines on the go which only seem to produce +6 iron per turn. Anyway, every time I get near having enough to finally upgrade a warrior (with the requisite gold of course) - the iron seems to reset and I have to wait to get there again! I notice one of my cities (a brand new one) seems to switch from warrior to legion for some reason - is this something to do with it? Even when I switch it back it wont give me the iron back. Very frustrating! Am I missing something obvious?