All connected devices showing 0% usage

Our data usage has been increasing every month.  Last month was our courtesy month, and so far this month we're on pace to use 115% of our 1.2 TB.  We do have four people in the household streaming video, working from home, taking online classes, etc. so I'm not denying our usage may be very high, but I'm trying to understand it better.

With either a PC browser directed to https://internet.xfinity.com/connect, or via the Xfinity app on my android phone, I am able access a list of all devices connected to my router.  I see all the devices I expect, and none that I don't.  So that's good.  What isn't good is that every device reports 0% network activity.  0% today, 0% 30-day average. How am I supposed to troubleshoot my high usage without this information?  Is there any way to get it working?  Googling the problem has mostly turned up numerous threads, all a year old or more, all reporting problems, none reporting solutions.