How to disable iPhone Calendar alerts for new events?

When I add new events to my iPhone, I don't want alerts.

I set the setting Alert to 'none'

Then after the event is created an Alert for '10 minutes before' is automatically applied.

This is very frustrating. I don't want the alert.

What's the issue on my end that's causing the event to have an alert when I create new events? I don't want any alerts.

[Re-Titled by Moderator]

Original Title: iPhone Calendar Alert - set to None, then automatically set to 10 minutes