Can't turn my smelters on

I bought a couple of smelters in Iron Will mode and left them running as meteors came in to build up my iron. However, they have somehow shut themselves off and won't turn back on. When I click the [+] to enable one it blinks green and turns right back off.

I have both wood and minerals and I have 100 iron left before I'm maxed out, so why would my smelters refuse to run?

Solution 1:

In Iron Will mode, smelters automatically cut off when you reach 95% of the cap, in order to preserve resources. If your current iron cap is 2000, then this fits exactly with stopping 100 before the cap.

Source: buildings.js, line 448-453:

//safe switch for IW to save precious resources, as per players request
if (game.ironWill && iron.value > iron.maxValue * 0.95){
    self.enabled = false;
    self.on = 0;
    return;
}