Blacksmiths on strike?

I just built a second blacksmith and upgraded it. The first one has 8 workers. The professions window says that I have 8/8 blacksmiths. THE +- buttons on the new blacksmith will toggle the occupancy slots between "Slot Disabled" and Unfilled, but the number of smiths does not go up. I have toggled it in and out of production status, I have quit and restarted the game.

https://preview.redd.it/hadrwm75jojg1.png?width=1920&format=png&auto=webp&s=4503701941f16481725265ae48a8796fb0cb67f5