There seems to be a fairly recent bug affecting track play counts–or plays–when the played count property of an iTunes track is changed with AppleScript. If iCloud Music Library or iTunes Match is enabled, the value will revert to what it was before being changed by AppleScript. It seems as though either the new play count for a track doesn’t get synced to the cloud or that the original value in the cloud has over-written the new plays value. Or something like that.
Several scripts here (Multi-Item Edit, New Play Count, New Last Played Date, et al) that allow you to edit the play counts of your tracks are affected by this bug, which only occurs if you’re also using iCloud Music Library or iTunes Match. I am not sure if versions of iTunes prior to 184.108.40.206 are affected or if, perhaps, the bug also occurs with a track’s skipped count (I wouldn’t be surprised).
I filed a bug report with Apple and it turns out it’s already an open issue, so Apple knows about it. Now we wait.