Until a few days ago, i could see a preview of my opend firefoxwindows on my taskbar (Windows 10). If i hover over the firefoxlogo on my taskbar now, i get all my tabs shown with their title, but no preview of the opened windows.

How do i fix this? When i tick the option "show previews in the windows taskbar" Windows 10 shows me all of the tabtitles, but still not the windowspreviews i had up until a few days.