Strange icon on the screen...?

What happens if you press the 'down arrow' button (on the left side of the device) while this is displayed? More Information displayed, perhaps?

Have you updated the firmware to latest version yet? I am on 2.80 (latest as of today) and I never see that screen. Maybe you need to update firmware?

Thank you for suggestion to press down key, for some reasons I didn't do this simple step

It seems this enigma is uncovered now. I need to repeat steps when I first time seen this icon. I pressed down key and screen says "You Have Arrived" (or something similar). It was happened cos I had used navigation to the Waypoint, and when you passed destination Waypoint this icon (I guess) indicating something like navigation is done.

I am on 2.80.

Ahh, excellent! I will use my Mini to navigate to a waypoint to verify operation.

I believe that this is actually a variation of the "home" screen. This is one variation when routing is in progress. 

Unlike the other screens in the up/down rotation, the home screen shows different things depending on the current/recent activity. You can tell it's a variation of the home screen because the status bar is shown. Other screens have a screen title instead.