I had trouble with Google Calendar Sync (GCS) deleting some of my Outlook calendar items when I set it up for 2-way synch between Outlook and Google. Then I dialed it back to 1-way sync, and found that some Outlook items weren’t getting copied to Google. Bummer.
I looked in “C:\Documents and Settings\kk4056\local settings\application data\google\Google Calendar Sync\logs” and found the error message:
Participant is neither attendee nor organizer
Well excuuuuuse me! For some reason, if Google doesn’t see your email address in the invitation (perhaps you were a BCC?), it refuses to add what it considers to be someone else’s appointment to your calendar.
In my case, my Exchange ID was something like email@example.com. I went to GMail, and told it that I sometimes send email as firstname.lastname@example.org, and now it believes that appointments for email@example.com are appointments for me.