Essentially, the issue is the GAL is not updating in Outlook. I looked at the recipient filter of the GAL, it's below for reference: (Alias -ne $null -and (Object Class -eq 'user' -or Object Class -eq 'contact' –or Object Class -eq 'ms Exch System Mailbox' -or Object Class –eq 'ms Exch Dynamic Distribution List' -or Object Class -eq 'group' -or Object Class –eq 'public Folder')) The next thing I'm going to try is creating a new GAL and making it the default, if necessary. That will force Outlook to download a complete GAL. If so, it is probably that the incremental update files haven't updated correctly.
I ran the commands you recommended and tried it about 4 hours after that. As another way to troubleshoot the problem, I created a new profile for Outlook.With that constraint lifted, the primary design goal for Exchange 2016 is for simplicity of scale, hardware utilization, and failure isolation.With Exchange 2016, we reduced the number of server roles to two: the Mailbox and Edge Transport server roles.Learn about the new features that are available in Exchange 2016 when you upgrade from previous versions of Exchange.Microsoft Exchange Server 2016 brings a new set of technologies, features, and services to Exchange Server, the messaging platform that provides email, scheduling, and tools for custom collaboration and messaging service applications.