If you first added a View block to a page and created a new View, and now you want to re-use the same View on another page, you should edit the second page, insert a View block, and choose to use an existing View rather than create a new one.
It doesn't work for me. When I click on "Edit Copy", it rather leaves the page and take me to a single user page instead of creating a copy of the view.
I'm not sure what "a single user page" is, perhaps we could take a look at your site to see for ourselves what happens?
Let me mark your next reply as private so that we can get log-in credentials from you—you may want to create a temporary admin user for us to use that you can later delete. And be sure to have a current backup of your site.
Which page has the copy of the View, as shown in your screenshot?
Thanks for the tip. I knew exactly what could cause the issue immediately I read your reply. The problem was caused by the Stackable -Gutenberg Blocks. It's a pity because I would have really liked to use both Toolset and Stackable together.
