Recently ran into an issue where an organization could not view public folders within Outlook once users where moved to Office 365 (Exchange Online).
The organization was running Exchange 2013 on-premises. They had already converted public folders to public folder mailboxes. We had setup ADFS with Office 365 and had completed an Exchange 2013 Hybrid implementation. We had migrated a few test accounts to Office 365 and everything appeared to be working perfectly – until we realized public folders were not showing in Outlook.
One caveat: The public folders will still not be available in Outlook Web App (OWA) until the public folders are migrated to Exchange Online.
Jacob Eker, PEI