It's when I'm running a venue business as a playable sim and try to sell tickets to customers. So far it's only happened when Dazzling, but because it's so rare I can't be sure of that. So what happens is that very rarely, easily several sim days apart if I play the business continuously, a sales action will fail. It just disappears from my sim's queue, and the sim may jump a bit. The customers jump and start browsing the ticket machine again, and the price of the tickets may change (usually to what the game considers an "average" price). The playable sim can also become "confused" at the jump, that is, when I move the cursor the sim just turns around on the spot even if the game is on pause.

It seems that I can gain control of the playable sim again if I make them do something else, like "go here". After that I can continue sales and re-set the price if necessary. So it really seems to be just an annoyance, but it would be nice to know what it is and if it's a non-critical hack, get rid of it.