2016 – Sharepoint Calendar Sync with Outlook not showing multiple day events

I have a SharePoint 2016 calendar with customised event content types. I synced it to my Outlook (Exchange, 2016) and it sync fine, I can view the calendar and events in my Outlook.

However, multiple day events only show me the first day of the event. It is a holiday calendar so I really need to be able to view the full event, not just the first day.

Even when I click on the event, it says start and end day being one day, despite the event in SharePoint Calendar being a week and showing correctly on SharePoint.

Any help would be appreciated.