Me too - I don't think I had this problem before, but I just realized that many of the tracks I've purchased in iTunes have had their play counts reset to zero. I believe this happened during my three-month trial subscription to Apple Music - I knew that lots of metadata in those files got messed up, but I only just noticed that many of the play counts were also reset. But there's also a possibility this has happened since my Apple Music subscription ended, a month or two ago I guess - I thought I'd gone through and fixed the metadata alterations, but I've just had to spend a few hours doing that (again? or for issues I hadn't noticed before?). I do not use, and have never used, iTunes Match.
For what it's worth, all of these plays = zero tracks still have a last played date recorded. The reset is oddly random - I've got plenty of albums with play counts like 17, 17, 17, 0, 17, 0, 17, 0, 0, 17. The ones that are reset to zero are also almost always the ones with messed up metadata.
Very annoying. So much for all those playlists based on most played, least played, and so on.