Horizontal scroll bar

Why is my horizontal scroll bar at the bottom of the mix console disappearing when I open the mix console? I have to click on the Control room tab to make it reappear. Any clue? To scroll from left to right although I use my Logitech Wireless Mouse MX Master2S which has a wheel for that. Very handy, but sometimes doesn’t work so I have to use the scroll bar. Another Cubase mystery… but I like it!