Bugreport: all day event displayed at 00:00 if start and end date are the same day

The website https://www.webcal.guru/ is providing interesting web calendars.
In EM Client the all day events eg. a holiday in the US Federal Holidays calendar are shown at 00:00. In other applications e.g. Outlook or Calendar on iPad these events are displayed correctly. I could find the reason by manipulating the ics files. Events with DTSTART and DTEND at the same date are shown at 00:00 of this date. Despite of the flages
X-FUNAMBOL-ALLDAY:1
X-MICROSOFT-CDO-ALLDAYEVENT:TRUE
are set and the value is declared as date.
Only if DTEND is one day later as DTSTART the event is shown as all day event.

Examples:
This event is shown as event the 9. May 2021 at 00:00:

X-FUNAMBOL-ALLDAY:1
X-MICROSOFT-CDO-ALLDAYEVENT:TRUE
DTSTART;VALUE=DATE:20210509
DTEND;VALUE=DATE:20210509

This event is shown as all day event the 9. May 2021

X-FUNAMBOL-ALLDAY:1
X-MICROSOFT-CDO-ALLDAYEVENT:TRUE
DTSTART;VALUE=DATE:20210509
DTEND;VALUE=DATE:20210510

To manipulate the ics file ist not a option for webcalendars, so it would be nice if you could fix this bug.
I have EM client version 8.2.1237 on windows.
Kind regards
Gerard