Copied/pasted this from the Office 2016 for Mac Preview forum (http://community.office365.com/en-us/office_2016_preview/f/991/t/350352.aspx), but I'm seeing this also with Outlook 2011 for Mac.  Also posted here.

Hi,

I'm running the latest preview release of Outlook on my Mac (the entire suite actually), specifically version 15.10.0 (150508).  We've run into the issue with numerous additional users as well where we need the following scenario met:

- Free/Busy time only for the Default User.
- Need to set FolderVisible so that every user can open the calendar with theirs.

What we're running into is that although you can check it and save it, when you close out of the permissions and re-open them, the change is not actually saved.  We note, however, that Windows clients do not experience this issue, and in fact, their role/permissions level then becomes 'Custom'.

One other point to note, and I have issues with it, is that when I tested on my own user account, I see this when checking via PowerShell:

FolderName User AccessRights 

---------- ---- ------------ 
Calendar Default {AvailabilityOnly}

What I don't see, and also cannot set via PowerShell, is whether or not FolderVisible is set.  I have looked at this article on Technet for this purpose.

 https://technet.microsoft.com/en-us/library/ff522363%28v=exchg.150%29.aspx

I think this is a bug, both at the PowerShell level, but also at the Outlook for Mac client level as well.  I seem to only be able to set this via the Windows client.  Also, while we're specifically wanting this against 'Default', this has proven to be the case even if we attempt against actual users.

Thanks!
Scott