Missing function key in screen picture

Hey,

I had a small problem. Every time, if you hit Fn+F2 key in the M17x, you will see a picture in the screen to indicate you whether your function is running or not, right?

Since last week, I found when I use that function key, the function is running but I can not see the icon picture any more.

Did I miss some files? how can I bring that nice picture back? any have idea?

Thank you so much for your help!