Sometimes when I create a calendar event and begin adding in alerts for it, the event will randomly auto-delete all of the alerts. Here is a screen recording of this happening.
https://vimeo.com/user107142004/review/382625926/e9c52eacd3
Let me know if you know why this is occurring, and if you have experienced it too.
EDIT: I go to add alerts for the event in calendar (I like to have many: 30 min before, 2 hours before, 2 days before, 5 days before, etc). Sometimes the alerts I create simply disappear, and it goes back to the default. There have even been other times where I add alerts, and they show up on the event, but when I close the app and re-open, the alerts that were previously there are now gone.