Outlook Email view graphics problem

Anyone have an idea how to clear up display issues in the Outlook email user interface? On Windows 10, Office 365, Dell XPS-13-7390 updated. The Outlook email list shows a graphics glitch on the left inside the field header line just above sort headers. The glitch is a row of gray crosshatching bar with a black bar beneath, extending from the left through the first couple of headers. I have a screen clip.