I have multiple bartenders on the Isle of Awakening and corresponding bars, but they never seem to be making drinks and seldom if ever stand behind the bar. I've tried placing chests with ingredients in the bar area, but to no avail.
I'm not sure that bartenders are actually supposed to do that, but recruited corpse monsters have it listed as a specific skill, and my corpse monsters just stay around the animal paddock all day.
Best Answer
It looks like a bar is not enough to get bartenders to make drinks. You actually need a Potable Plant. The potable plant is suggested by one of the townspeople. The recipe is:
The weird thing is I can't get my bartenders to make drinks, but some others do.