Here is the message count workaround I use on the Mac:
In the "New" Outlook ...
- In the left panel, select the Inbox, or any other folder that you want to see a full message count (read and unread).
- Click anywhere in the message list area and Select All (command-A on a Mac).
- The message window will now display an envelope graphic with "XX conversations selected".
This gives you the message count for the folder selected.
FYI. Why Microsoft labels them as "Conversations" instead of Messages is beyond me. If you view your messages as "Show as Conversations" the count is actually the number of grouped conversations, not the number of all messages.
You're welcome.