[Plugin: ICS Calendar] problem with showing events on multiple dates

I have the option switched on to show events on multiple dates, but when I have it switched on, some single day events seem to be left off the calendar.

please see the upcoming events list in comparison to the calendar.

https://wordpress.oxfordinspire.co.uk/?page_id=2

# Thu, Mar 4: Lanzarote Training Camp
More Details on activeglobal.com (Las Palmas , Spain)
# Sun, Mar 7: Maidstone Duathlon
More Details on activeglobal.com (Kent, UK – England)

This data is based on this calendar

https://www.oxfordinspire.co.uk/triathlete/europecalendar.ics

many thanks.
seem to be missing.

https://www.ads-software.com/extend/plugins/wordpress-ics-importer/