I dont know how to describe that portion of taskbar so I will rather post a screenshot upfront :

Yes, the background is part of the desktop wallpaper and it's always like that, but if you hover the mouse pointer over it, part of it will turn grey . It's kinda annoying coz I cant see the time on 2nd monitor clearly. I'd be much appreciated if someone could advise me with a possible fix. This app is nearly perfect to me (even better than ActualMultipleMonitor I had used for long time) except this minor but annoying issue

I dont know why my image on the first post doesn't seem to show up after I revisit this post. So this time i re-uploaded with the attachment function.

Here it is.

Yes. Disabling it solved the issue completely! You are amazing!
Sorry to have you gone through the lengthy file and debug work!