I'm using the latest WP (2.7.1) and latest AmR plugin. I have a calendar of birthdays, so all events are single, all day events that recur yearly. All events are showing great if I do a list of them on a page, however, some are skipped I have a widget display the next 5.
In case it's heplful; ics-calendar importer plugin seems to skip the exact same events with that widget (and list them all in the list on a page). Both plugins appear to have been written with the same base ics importer.
Message me for my ics for testing