ical multi-full-day is missing one day - calendar

Question

If I have a multi fullDay event in my generated ical, it is missing the last day. Screenshot of the calendar below.
This ical event MultiFullday should be from 21/05 - 24/05 (21 and 24 included), but 24/05 is excluded
BEGIN:VEVENT
DTSTART;VALUE=DATE:20170521
DTEND;VALUE=DATE:20170524
UID:590b6335922a5
DTSTAMP:20170504T192157Z
LOCATION:
DESCRIPTION:
URL;VALUE=URI:
SUMMARY:MultiFullday
END:VEVENT
This ical event Test Fullday should be only on 25/05 and it is.
BEGIN:VEVENT
DTSTART;VALUE=DATE:20170525
DTEND;VALUE=DATE:20170525
UID:590b63359237b
DTSTAMP:20170504T192157Z
LOCATION:
DESCRIPTION:
URL;VALUE=URI:
SUMMARY:Test Fullday
END:VEVENT
The events are wrapped into this
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Vereinsplaner//Vereinsplaner v1.0//DE
URL:https://www.vereinsplaner.at/ical/user/58b7118b6d716e7478abb2.ics
NAME:Vereinsplaner
X-WR-CALNAME:Vereinsplaner
DESCRIPTION: Termine von Vereinsplaner.at
X-WR-CALDESC:Termine von Vereinsplaner.at
X-WR-RELCALID:VereinsplanerCal
COLOR:11:174:219
X-WR-TIMEZONE:UTC
X-PUBLISHED-TTL:PT1H
CALSCALE:GREGORIAN
METHOD:PUBLISH
... // Between here
END:VCALENDAR
When i import the ical, this is the result. As you can see the multi fullDay event is missing the last day
According to this Mulit-Day All-Day Event , my DTSTART and DTEND are in the right format.

Answer 1

In the meantime i solved this problem by adding a day to the enddate.
According to this Fullcalendar end date wrong by one day the enddate is not included.
instead of
DTSTART;VALUE=DATE:20170521
DTEND;VALUE=DATE:20170524
I write
DTSTART;VALUE=DATE:20170521
DTEND;VALUE=DATE:20170525
I am open for any other solution. But maybe this answer will help anybody else.