The user that reported this is signed up for an event on October 17, with 5 and 1 day reminders. Shouldn’t his reminder1_sent value stay at 0 until October 12?
Yes, and those emails should not be sent until 5 days before the start time. Again, sounds like some issues with database values not being read or updated correctly. In this case, dates might be saved or retrieved incorrectly.
The last several updates I did were some fixes to use the WordPress date/time instead of server time (due to a user reporting issues because their server was in a different time zone), but I have tested and everything works fine still here (and for that person). I also just created my own test single date event for October 17 with 5 and 1 day reminders, and signed up, and hit the Send Reminders function several times… no reminders sent on my dev machine (XAMPP install on Windows 10).
Makes sure that user has their WordPress date/time set correctly, although I doubt it’s THAT far off! =)