Black box in corner of display

[AADR1504]

I have a FURUNO FR-2825 radar in which a black box appeared on the display in the upper right corner, covering approximately 25% of the screen and obstructing the radar information. There are no alarms.
Can someone please assist?

 

[Johnny Electron]

The FR-2825 is a commercial product not discussed here but clearly the monitor has the Picture and Picture (PIP) function turned on.