I know this is an older thread, so apologies if posting is in poor form, but I, too, encountered this issue. The bartender stood outside and did nothing for several in-game hours instead of tending the bar.
I was able to work around it by shift clicking the mixologist (with testing cheats enabled), clicking "Reset Object (Debug)" and then having my sim use the "Call Over" interaction on the mixologist. Once the mixologist came inside, my sim did NOT start a conversation with him. The "Call Over" interaction was the only social interaction I used. The mixologist stood there and stared at my sim for a few minutes and then went to the bar and started tending it.
I DO think this may be a bug of some sort, but I'm not sure what's triggering it. It happened during the mixologist shift change in my game, so maybe something else happened that interrupted the script that directs the bartender to go to work and/or caused the action to get dropped from his queue somehow and he "forgot" that he needed to tend the bar?
I've noticed that actions DO tend to get dropped from queues quite often, even ones that I assign to my sims, and it causes a lot of problems. Autonomous actions seem to override assigned ones in terms of priority, which is the opposite of the way it should work. My sim will refuse to eat when I tell her to sometimes because she wants to play with the cat instead. Even if her hunger bar is in the red, she will refuse to eat if she wants to play with the cat and I have to fight her to keep her from starving herself to death over the cat (and no, she doesn't have the cat lover trait.)
It happens with actions that are supposed to be automatic, too. One of my kids refused to go to school and was 3 hours late for class because he was bound and determined to wash a dirty dish instead no matter how many times I canceled the "clean up" action and tried to send him to school instead. The things he NEEDED to do (and anything I told him to do) got dropped in favor of an autonomous action that ultimately wasn't that important and could have waited.
Stuff like that really shouldn't happen, and I suspect the mixologists standing outside instead of tending the bar may be rooted in the same problem that causes other queuing issues and is likely related to which actions take priority in a sim's queue in the game's code. Things like going to work shouldn't be dropped from queues and overridden by a sim's autonomous whims...but that does happen, and it results in mixologists who won't tend the bar (and other NPCs who won't do their jobs, like firefighters who stand outside and do nothing while a house burns to the ground and sims who refuse to listen when you tell them to extinguish it themselves).
I know we have the option to turn off autonomy, but that kills so much of what can make the game enjoyable. Autonomy gives the game character and is a wonderful feature when it works properly...but it's game breaking when it doesn't.
If there's a way to tweak the script and set priority levels for various actions in a sim's queue, (1. Necessary actions like going to work/go to school, 2. Player directed actions, 3. Autonomous actions chosen by the sim) it would help a ton in terms of the game's functionality. ,
Anyway, I digress...
TLDR
If your mixologist is standing outside and will not come inside to tend the bar:
Press Ctrl+Shift+C to open the cheat console
Type testingcheats on
Shift+Click the mixologist and choose "Reset Object (Debug)"
Have your sim use the "Call Over" interaction on the mixologist
Then, do not engage! Ignore the mixologist after you've called him/her over, and he/she will go tend the bar like he/she is supposed to do
This workaround proved to be effective in my game, so hopefully others will find it helpful as well.
Cheers! 🙂
UPDATE - 3/6/23: This workaround no longer works. No matter what I do, the bartender stands outside the lot and plays with his/her phone instead of tending the bar. Sims can't order drinks at venues at all anymore. Bar Nights are pointless. Bars themselves are pointless, as are Nightclubs and any other lot containing a bar.
Bartenders are flat out broken and do not work at all. Cheers revoked.
