This does happen all through the client interactions, you have to chase them all over the place. The thing with the interactions cancelling is an old bug since life and death base update. If you watch carefully you will see sometimes like a reset happened. All queued interactions disappear you could try pausing the game as soon as the last interaction has completed then move on to the next thing you have to ask. It at least stops them walking away. The client throwing up in the loo is a bit of a nuisance too, it distracts your sim and the client .
