Have you checked the log when trying to record?
Opening the terminal and running journalctl --follow and starting the recorder output anything informative?
In my situation the following is the only thing I can trace in the log are these lines
dbus-daemon[1630]: [session uid=1000 pid=1630] Successfully activated service ‘org.gnome.Shell.Screencast’
Alternatively trawling the entire log for the current sessions is an option and fitering for the screencast:
journalctl --boot | grep 'org.gnome.Shell.Screencast'
Adding your system information to the first post will help get better feedback & support for the issue. It will also help other with similair problems find this thread later if it is solved.
Please share it formatted as detailed here