Yeah, I’ve had this happen to me, twice. 
I’ve found that it is usually because of funding cutbacks (no money to pay salary) or they have run out of funds/time to interview anyone else. I could very well be wrong, but, that’s what I think.
Nothing is as gratifying and disappointing as " We love your stuff and would love to have you as part of our design team, but funding has just been cut, so we can’t afford to hire anyone. Thanks…" You just have to laugh about it and not take it personally. I hope that helps to answer your question. 