Dashboard - Focus mode

Hi, 

When I go from our dashboard with one of the visuals in 'Focus mode', I don't get information (as a screentip) anymore when i put my cursor on one of the lines. All I can see is this black coloured greater or less than icon. I used to get a screentip-like popup with the data of the line my cursor was above.
Can someone explain the meaning of this icon and why can't I see the values of the data anymore?

Thanks in advance

Hein

Edited:

The problem is that the box with the data is not shown. Only the icon, belonging to the box, is visible.

It looks like a problem in Edge. In FF and in Chrome the box (with the data) is shown correctly.

Thanks for viewing this issue!

Hein