Sudden zero population

[jkraska]

I'm fiddling around with various mods, and have mutated the growth scale only a little (4% versus 2% if I remember right).

In an experiment I'm running, population of a capital province one turn goes from somewhere in the 300,000's to *0*.

I can find no explanation for this at all.

Tax is 90.

There is no disorder.

There is no death scale, and no enemy candles.

There is no blood hunting in this province.

Any explanation?