I'm unable to view the top bar on SharePoint sites that has the settings gear and the notifications center. Nothing in our organization has changed recently. It appears again when I manually navigate to the settings url, however. The buttons should be in the black bar in the screenshot.
Is this a widespread issue or is there something I can do to solve this?
I occasionally experience the same behavior and refreshing the browser usually addresses the issue. If everyone in your organization is having the same experience as you, I would suggest contacting support.