I have the same issue. I can't order food at the Cottage Living bar, because the bartender does everything but tend the bar. Most often she practices tricks, but occasionally she just goes to sit with the other sims and talks to them instead of working.
I didn't have this issue before installing Businesses & Hobbies.
For what is worth, it’s not the BH expansion pack that seems to be the issue, but the update that went online just before its release. In the patch notes it had something about the Thriftea shop, so I guess the fix for that issue butterfly effected into other Service Sims, like mixologists.
