Seems something goes wrong with assignments. Miner count has a mismatch.
Are all your mines full of workers or are some only partially occupied?
All were full of workers, it was a on a switch after a purchase on the Trader. But the effect happened before on other buildings. The solution is also known; bring the count down to zero and reapply the workers.
Do you have steps to reproduce this issue?
Its very random, let me make a video next time it happens. Still not sure what causes it though.
