I exiled an opponent's creature with my own "Phelia, Exuberant Shepherd," while I put a stop at my own end step.(expecting to "Stifle" the coming back trigger which I had in my hand.)

The result was, the stop did not happen and opponent's creature simply came back, not allowing any window for me to interfere.

Not sure if this is Phelia's bug or the stop bug, but either way it happend :(