LlamaZoom not working

I've experienced a different LlamaZoom problem, twice this last week. I was in the middle of completing LlamaZoom quests (with just one left, the last one of 3 short events required) as part of the time-limited event to earn Photography career. I left my Sims to finish the task by themselves and disconnected. When I came back and the quest should have been finished, LlamaZoom had gone away ("returning in XX hours"), so the quest set wasn't completed and I didn't receive the LlamaZoom rewards, and consequently the Photography event requirement wasn't fulfilled either. I've lost a lot of time because I've had to repeat a full set of LlamaZoom quests, in two occasions, in order to complete the event requirement.