If no printer available, create a dummy one with `lpadmin -p myprinter -E -v ipp://myprinter.local/ipp/print' (per man lpadmin). WLOG, print something to `myprinter'. Open the "printers" part of gnome-control-center (Alt+F2 > Printers). Observe the button `1 job' and click it. In the `myprinter - Active Jobs' window, find the submitted job and press the trash can to cancel the job. With this fix, it should successfully cancel. Previous behavior resulted in nothing happening.