Using New Outlook on Windows for personal email, calendar, and contact management
Same problem on web platform.
It will only let me tab if I hit "enter" when typing the recipient's email when their full address is populated. But then only if they are within my organization. If I enter the full address manually - whether they are in my org or not, it will not let me tab away. If I enter an email outside my org - even when hitting 'enter' to select their entry that auto populates - it will not let me tab.