Signal tap with grey background

That looks like a graphical anomaly. If you close and reopen the .stp file, does it go away?

Or maybe do you have any sample qualification features turned on (i.e. only capture data when some signal is high)? If you do, it could be marking where samples were skipped, but it doesn't usually look like that. I would want to zoom in to be sure.

#iwork4intel

Hi, is the above suggestion works for you?

i still don't know the meaning of the grey highlight.

Can you share your .stp files so I can look into it.