Cubase Pro 9.5 mixing console "undo" is not working

Hey friends,I have upgraded to Cubase Pro 9 to 9.5 currently.But I am finding hard to undo-ing in mixing console.sometimes it works and sometimes it disappears.I don’t know whether it is a bug or not in Cubase Pro 9.5
please help me out as I have so many projects on my hand but I have to do the project again and again as undo isn’t working on mixing console.

I am using windows 7 64 bit

Yes! This is already reported, use the search first and you could join those threads.