Exact same problem here. No mods. Clean game with a fresh cache and everything. All packs except Bowling Night installed.
My vet greets the patient, they go to the exam table, my vet does the examination (having to get the pet back onto the friggin table like 3 or 4 times because it keeps leaving on its own which is really annoying), my vet successfully treats the pet and the cost of the treatment is deducted, but then the owner won't pay up! They just stand around the clinic with a simoleon sign hanging over their head. There's an option on the pet to bill the owner, but the action cancels itself every time I select it and the only way to make them leave is to dismiss them, but then they leave without paying.
My vet can't make any money at all like this. What is the point of the new vet career if it doesn't work? :neutral: What a shame, that's the biggest reason I bought the pack and I can't even use the pack's main feature.