This is as close to a place as I see to report bugs, so here goes.

Creating a recurring event that repeats on the last weekday of every month doesn't appear correctly on other calendars. Included at the bottom of this message is the meeting file that is created by Outlook when sending the meeting invitation. A believe the RRULE in the ics is missing a BYSETPOS=-1 that prevents this from acting correctly. Instead of ending up with an event on the last weekday of the month, I end up with events on the last Monday, Tuesday, Wednesday, Thursday, and Friday of the month (so five events instead of one).

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BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Microsoft Corporation//Outlook for Mac MIMEDIR//EN
METHOD:REQUEST
BEGIN:VTIMEZONE
TZID:Eastern Time (US & Canada)
X-ENTOURAGE-TZID:4
X-ENTOURAGE-CFTIMEZONE:US/Eastern
BEGIN:DAYLIGHT
TZNAME:Daylight
RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=2SU;BYMONTH=3
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
DTSTART:20140309T020000
END:DAYLIGHT
BEGIN:STANDARD
TZNAME:Standard
RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=1SU;BYMONTH=11
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
DTSTART:20141102T020000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
UID:0155F0C5-FCBF-4A02-A095-17E09AA7EA79
X-ENTOURAGE_UUID:0155F0C5-FCBF-4A02-A095-17E09AA7EA79
DTSTAMP:20140527T164700Z
DTSTART;TZID="Eastern Time (US & Canada)":20140530T000000
DTEND;TZID="Eastern Time (US & Canada)":20140531T000000
LAST-MODIFIED:20140527T165800Z
SUMMARY:Test Event
DESCRIPTION:\n
ORGANIZER:MAILTO:*** Email address is removed for privacy ***
SEQUENCE:0
RRULE:FREQ=MONTHLY;INTERVAL=1;BYDAY=-1MO,-1TU,-1WE,-1TH,-1FR;WKST=SU
ATTENDEE;ROLE=REQ-PARTICIPANT;RSVP=TRUE;CN=*** Email address is removed for privacy ***;PARTSTAT=N
 EEDS-ACTION:MAILTO:*** Email address is removed for privacy ***
X-MICROSOFT-CDO-BUSYSTATUS:FREE
X-MICROSOFT-CDO-ALLDAYEVENT:TRUE
X-MICROSOFT-CDO-INSTTYPE:1
END:VEVENT
END:VCALENDAR