Using classic Outlook for Windows in business environments
If you clear the blue unread status by clicking the email or by clearing the small envelope icon on the email, it will NOT clear unread status on the gmail account. However, if you select one or more emails then select "mark as unread" then select "mark as read" in the X items selected panel to the right, it will clear unread status in the gmail account. A bit of a pain but a way to get by until they fix this.