The Pause/Break key makes the marker move smoothly v ju,ping one beat at a time.
The computer scroll key makes the project scroll or not.
The is a scroll on/off button on the VS-700 that is unfortunately by the jog wheel. It can get bumped and stop scrolling. (I don't see your euqipment list.)
Just to be sure, under View | Display, there is a thing called Aim Assist that helps you see where you are located when you are editing. It is not the same as the Now marker and can be confusing. It does not scroll. I tunr it off unless I am doing detailed clip splitting or something similar.
If the tracks are scrolling and the Now marker is disappearing, I have no idea.