Hi Pushpak
I don't know exactly as the incompatibilities vary between versions and are around multi day events not being supported.
The new Microsoft Outlook version, often called "Outlook (New)", has issues with importing .ics files, specifically when double-clicking them. While the older "Classic" Outlook handled .ics imports seamlessly, the new version requires a multi-step process or may not import at all
There is a global seminar setting Send multiple confirmation emails for multi-date events. that may help in Outlook if using legacy notifications
If there is more than one event date on a single day then each session will generate an email. One session spanning over multiple days will generate only one email.
Regards