Default alerts from calendar events not showing up in Outlook

When I create an event in my calendar on my iPhone (iOS 17.3) and use the default alert time, this alert will not appear in Outlook (on my desktop PC). The event shows up in Outlook, but with no reminder.

If I create an event from my iPhone and manually choose a different alert time, the alert will appear properly in Outlook.

Help! This problem has caused to miss certain appointments, because reminders are not appearing on my desktop while I am working!

(my email is an exchange account. I have spoken with technical support with Intermedia and they have been unable to fix it.)

This has worked properly for years - this is a new problem.