.ics Calendar issue with Exchange 365, Apple Calendar App

I have the same issue like here: .ics Calendar issue with Office 365 - Apple Community

Since iOS 16 (iPadOS 16) I cannot import .ics files into my Microsoft Exchange 365 calendar account using the iOS native Calendar app.

Creating the appointments manually works fine. .

Using the Microsoft Outlook app also works fine.

Importing the .ics file into iCloud instead of Exchange 365 calender also works.

I tested it on two different iPads with separate Exchange-365 and Apple accounts. I tested ics files from different sources (airlines, crm, ...). I removed and recreated the accounts on the iPad, restarted the iPad several times, changed default calendar account, and so on).

In my opinion, it seems there is a problem with the native iOS client for Microsoft Exchange calendar...

To reproduce the issue: Send the following .ics file via eMail to an iPad with iOS > 16. Open the file in the native eMail app and add it into a Microsoft Exchange 365 calender account.

Afterwards check the calender via outlook.com or on another device.

Please find an example file as follows:

BEGIN:VCALENDAR

PRODID:ABC

VERSION:2.0

METHOD:PUBLISH

BEGIN:VTIMEZONE

TZID:W. Europe Standard Time

BEGIN:STANDARD

DTSTART:16011028T030000

RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10

TZOFFSETFROM:+0200

TZOFFSETTO:+0100

END:STANDARD

BEGIN:DAYLIGHT

DTSTART:16010325T020000

RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3

TZOFFSETFROM:+0100

TZOFFSETTO:+0200

END:DAYLIGHT

END:VTIMEZONE

BEGIN:VEVENT

DTSTART;TZID="W. Europe Standard Time":20230329T153000

DTEND;TZID="W. Europe Standard Time":20230329T163000

TRANSP:OPAQUE

SEQUENCE:0

UID:10020594-ABC@abc.de

DTSTAMP:20230327T131900

SUMMARY:Test

PRIORITY:5

X-MICROSOFT-CDO-IMPORTANCE:1

DESCRIPTION:Test

LOCATION:Test city

CLASS:PUBLIC

END:VEVENT

END:VCALENDAR

BTW: some ics files work if they contains following part. But also not all files.

BEGIN:VALARM

TRIGGER:-PT15M

ACTION:DISPLAY

DESCRIPTION:Reminder

END:VALARM