I have a similar issue. I can create calendar appointments, but the alert time saved in Agenda doesn’t turn into an alarm/reminder in Outlook. The calendar I’m saving the appointments in is an exchange account.
The odd part is that everything else seems to work correctly with calendar events. For example, I can create an event in Agenda which appears in Outlook. I can modify the event in either calendar and have the changes sync’d to both. I can delete a calendar event in Outlook and have it go away in Agenda. BUT, no reminders in Outlook (even though they show in Agenda) mean I miss appointments and tasks created in Agenda since they don’t pop up at the correct time.
I can add the reminder time manually in Outlook and it will update in Agenda. But Agenda doesn’t seem to be able to pass the reminder/alert time to Outlook.
Outlook reminders rule my life. Agenda can help tame my workflow, but only if the pop-ups trigger in Outlook.