Organizing and accessing contact information in Outlook.com
Update: I also have Outlook.com pinned as a PWA. It was suffering the same problem. It was open. I just refreshed it and the Contacts scrollbar has returned and it's working as expected.
However, in a browser tab, refreshing didn't produce the same result. So, I closed the open tab, opened a new tab, opened outlook.com, clicked Contacts. And it's working!
I'm using Edge (Dev) browser.
UPDATE 2: I spoke too soon. I just refreshed both the PWA and the browser tab. The problem has returned. 😟