I’ve had this happen sometimes on my iPad, but it’s rare. It’s happened in some arena battles and I think at most twice in PVP. Some of the time, after this happens either I or the enemy will make a match, and one of the gems doesn’t fall right, leaving a blank space; the opponent never makes their next move. Other times, the opponent starting doesn’t affect anything.
I believe this is likely also related to a bug in the Treasure Hunt minigame, in which the first turn sometimes happens without you. When this occurs, the board “jitters” as if a match was made and I have 14 turns left. However unlike the opponent-starts-first bug, the minigame does this about half the time.