iCloud Calendar Event Alert not syncing across all devices

[icanhazmac]

Hi all, I have an interesting one:

I have a family shared calendar between my wife and I and I have found that when changes are made to appointment alerts the alert is not updated across all devices, as an example:

A birthday calendar event has an alert (1 day before) which triggered on my MBP but not on my iPhone or iPad. Upon inspection I found the calendar event on my MBP had the alert listed but there was no alert for the entry on my other devices. This means notifications are not the issue but the event sync across iCloud to my other devices... the event is there and sync'd but the alert is not. Further testing reveals that if I make a note change on my MBP that info syncs to my iPhone and iPad while the alert remains "none". I can also make a notes change to my iPhone which syncs properly to my MBP.

All my devices are properly logged into my iCloud account and setup properly (to the best of my knowledge).

Throwing my hands up on this one.

Edit for further testing:

If I add an alert to a calendar event on my Mac it will sync to the iOS devices but the original alert does not.
If I modify the original alert on my Mac it will sync to my iOS devices.
If I modify the original event on an iOS device and add an alert, the new alert will sync as a second alert on my Mac, leaving 1 alert on iOS and 2 alerts on Mac.

One possible thought... my wife might have created these calendar events on her iOS device or Mac but under her calendar THEN reassigned the events to our shared family calendar. Will test further as time allows.

 

[T'hain Esh Kelch]

I just tried to fix my own issue, which seems to be the same, so I will just add this here in case you still have issues. My default alerts didn't work, and were not synced over iCloud. Normal alerts worked just fine. I pretty much only use the macOS calendar for creating events, so I am not sure if this was the problem. In any event, I tried creating a new event on iOS, with a default event set, and then suddenly everything started working - Also for macOS Calendar. As if there were some bad electrons that needed to be flushed out somewhere in my iCloud calendar sync pipeline.