Also I have two own CUPS backends (in fact, it is just 'pstops' convertion) - printers based on these backends don't stall in processing - rather successfully directs a job to real printer mentioned above (Kyocera), and this way got job for Kyocera does stall also.
The problem isn't related to, say, apparmor - stopping the service (and restarting CUPS) doesn't help.
Additional information.
Also I have two own CUPS backends (in fact, it is just 'pstops' convertion) - printers based on these backends don't stall in processing - rather successfully directs a job to real printer mentioned above (Kyocera), and this way got job for Kyocera does stall also.
The problem isn't related to, say, apparmor - stopping the service (and restarting CUPS) doesn't help.