Calendar creating random alerts for events

The last couple of weeks, iCloud Calendar and the Mac Calendar having been doing something very odd. I have my college courses laid out in my Calendar and syncing between my iPhone, Mac, and iPad. My default setting for this college calendar (and across my devices) was to alert me 15 minutes before each class started.

The last couple of weeks, however, the Calendar would alert me at my default time, but then it would alert me at the time the class was scheduled to start, and then at two random times after the class already started. The other two created alerts usually happened around 5-15 minutes after the event already started. After the second later time, the alerts would stop being created and stop appearing in my notifications. I was even able to watch these alerts being created, and if I deleted the new alert, I would have to delete it a second time before it actually disappeared. And this reminder went out across my 3 devices.

Here's what I have tried.

• Changed my password on iCloud/Apple ID
• I have removed the PList from Calendar app on my Mac, which changed nothing.
• Repaired Permissions with Disk Utility and Onyx, also did nothing (though Disk Utility at one point did detect an error in Calendar which it said it fixed).
• I went to iCloud.com and deleted the entire College calendar from the Calendar app and then manually re-added my classes. I noticed that on some the classes, it tried to create the random alerts immediately, but since I deleted those classes again and readded them and they stopped. This temporarily worked.

This last stepped worked for about a week before my college classes started doing this again. Since I applied the iCloud "fix", only some of my college classes have begun creating random alerts again, but only on my Mac and not on my iOS devices. Also, my birthdays imported from Facebook are now exhibiting this trait. No other calendars, such as my work or appointment calendars, are doing this though, and I have tested them by creating new events in said calendars. I don't want to stop using Calendar for something like this. Does anyone have any ideas?