I've had the problem in IE a couple of times, but not Chrome or Firefox and so far, it hasn't happened in Edge either. I use a wide variety of browsers at different times, because of my work.
I'm quite certain that it is not a browser-related issue. I've seen posts here about that happening a few times, so I know others have also experienced it. I have also seen that logging out and back in does not solve it, nor does closing the browser and reopening it. When it happens, it seems to last for an hour or two and then go away as abruptly as it came.