mix console tool bar disappears

I have issue with the mix console and his toolbar
When I resize the mix console from the top to the bottom, at a moment the Toolbar disappears and let me only the white bar
at the top
I can’t recover it, any suggestions?

I’ve had that, as well as the racks section disappearing, quite often (win7pro). It returns to normal after I restart the project. Still, bug for sure.