Iron Throne 3 achievement not triggering?

[Zaflis]

Not sure if i should post this on bugs or here, but maybe i don't quite know how this achievement is supposed to work. Should it be monitoring the iron plate production from 1 minute time frame, or do i actually have to keep the average of 400k iron per hour for 1 hour? Here's gameplay footage with over 400 furnaces. Long lines of them had full buffers of ore in many steel chests before i unleashed them all at the same time.

https://www.youtube.com/watch?v=cSnqY20VCIk

Playing Factorio experimental, currently 0.13.17. No mods and no console commands used.

[DaveMcW]

do i actually have to keep the average of 400k iron per hour for 1 hour?

Yes.