This has been an oversight I've wrestled with on some recent deployments. As far as I can tell, none of the dynamic overviews let you see that information out of the box.
I was able to wrestle the Context Visibility section into kind of what you are asking by adding the column for Endpoint Group and then filtering for value "Registered Devices". Once you do that, the Username field should show the device's owner. You can also drill into those individual records by clicking on one.
Also, if you go into BYOD > Reports > Registered Endpoints report you will get (user) identity.
The data are all in ISE's database, so it seems one should be able to get it to report out - possibly via API? I have't opened that can of worms though.