Calendar alerts not working on my MacBook Air

When I try to set an alert on day of event for an all day event it automatically reverts to no alert. I open the event in calendar, click on the alerts option, click on the "alert on day of event" option, and then it immediately reverts to no alert after clicking it. I also try on my phone and it does the same thing when I click done in the settings. I have event alerts enabled on the calendar I'm using.

[Re-Titled by Moderator]

Original Title: Calendar Alerts Not Working