What is it about Microsoft that makes it incapable of sticking to the rules? Internet Explorer has mangled HTML for years, so it should come as no surprise that Outlook has problems with processing some iCalendar files.
This particular problem has been around for a long time, and yet there still is no details offering a solution or work around available on the Microsoft support pages.
It is a testament to downright orneriness that software companies seem incapable of agreeing on and sticking to a single standard to allow seamless interchange of something as seemingly mundane as calendar information.
It is a glaring indictment on Microsoft that it fails to adequately support many open web standards that would make life easier for users, preferring instead to promote proprietary formats that serve no purpose other than to try and lock users in to its software platform.