We can’t create shape , impossible join the last vertex with the first one, when you do right-click then release, the menu disappear. I was following this tutorial
It could be an issue related to synfigstudio not being up to date with Wayland support. Please see if logging out and logging in using an X session fixes the issue for you.
Could you also please file a bug here on the Fedora Bugzilla so that the maintainer can look into it? You can login to Bugzilla using your Fedora account as you did here.