Using Classic Outlook on Windows for personal email, calendar, and contact management
In my case the issue is present when grammary is off or on, but the email highlight bar is jumping only when I have unread emails in the inbox and when I click on it. When all email are read no jumping.
The I wanted to figure out what is the pattern for this jumping, all the jumps were back to emails from 1/9, when removed these emails, then email started to jump to emails from 1/10.
I noticed when closing a email section like yesterday, last week, last month in in box the issue is gone. So I closed the last section in my inbox and works so far.