I can't dismiss hirelings from my stronghold. They don't have any status (e.g. "unpaid") and the hirelings menu only shows "hire" as an option. I also already recruited 8 in total, so I can't get new hirelings anymore. I tried to work around this by killing those I don't need, but that doesn't work. It would still pop up as 8/8 recruited and the hirelings I killed would simpy respawn when the area is reloaded. They do cost me money though and hirelings which were supposed to only stay for a limited time frame are now there permanently.
Steps to Reproduce the Issue:
I have no idea how to reproduce this bug. I hired 8 people pretty early in the game and didn't pay much attention for a long time. When a checked back much later into the game to dismiss some of them, the UI was stuck this way.
In my case, I hired the last three fighters.