I just saw this happen with both fishers in the same fishery. First, I got a notification that a fisher died of thirst. I went to the fishery to see if it had been replaced and I find the second one just standing in the stairs and the entrance and then it also died of thirst.
I kept playing, then saw the same bug on the lumberjack mill some time later. The lumberjack was standing in front of the entrance, with the red thirst icon. I tried using the kickstart power, but nothing happened, so I picked it up and try to gently drop it next to the well. After standing up, it went ahead and had a drink and hasn't gotten stuck since then.