I had this problem as well.
Exiting X1 and restarting sorted it for me.
I then made and saved a new project template with a preview bus added,
restarted X1 and all was fine [to date]
Not sure if it was a bug or not.
Everyday I keep stumbling upon new things in X1D [Good]
Today when I closed down X1, my screenshot 9 [PRV only]
was in View - of Course when re opening that project screenshot 9 was first up,
and my 16th note grid was still in view, and had not reset Itself to something else....Lol...
Garry