In this version of Firefox 61.0 the tabs are hidden in all the sites except the thumbnails of the Windows taskbar where all the groups of all the groups are shown together. I think it did not happen before. Just fix this so that the extension is perfect and 5*

Edit 1:

Thanks for your response. We hope that later it can be fixed (the thumbnails are very practical).

Another error that I have found is that when closing the last tab of a group, instead of appearing the Newtab page or disappearing this group, the last tab of the previous group is moved there. I've only been able to try it with 2 groups.