Recently users were complained they can’t see a free/busy availability of an Executive. When I looked the Executive user’s availability in my Outlook (in Meeting Request window), it shows hashed row of no information. I resolved it 3 troubleshooting steps.
1. I quickly contacted the Executive and told him to run "Outlook /CleanFreeBusy". It seems to be resolved and I can see his availability, but after a while his availability is not showing up AGAIN.
2. I know, historically, Outlook doesn’t publish free/busy if it finds any corrupted appointment. It used to error out with "Outlook cannot publish free/busy information…". With new versions of Outlook, this error message is suppressed. So, I checked the user’s number of items in his Calendar (change the calendar view by category to see the number of items). He had items since 2001. He archived his calendar and reduced the size of his calendar significantly. My only hope was the corrupted item is archived.
It wasn’t. His Outlook was not publishing the free/busy data.
3. I decided to take a look at his appointments one by one manually. I changed his Calendar view again to category. By checking the appointments one at a time, I finally found my culprit. It was Conflict in appointments. Few appointments were in conflict stage and showed twice. I quickly open the appointment and resolved the conflicts by selecting appointments with correct date and time. Finally I ran Outlook with /CleanFreeBusy option. It worked. Outlook is consistently publishing the free/busy time now.
Latest update: Look for any meeting organized by Non-Existent employees (who left the company and you deleted the account). This particular meetings (with no-account organizers) might be blocking Outlook to publishing the free/busy. This resolved one of the user’s calendar issue.
Hope it helps.