Problem solved.
As it turns out, the actual problem had nothing to do with the job size,
per se. Instead, it had to do with the time it took to produce the job.
From the looks of things, Lr makes the connection to the printer at the time it starts to build the print job. On my MacBook Air, producing that print job took over 5 minutes. As it happens, 5 minutes (300 seconds) is the default timeout period. So, most of the way through the job, it timed the job out, cancelled it, and marked it aborted.
Solution: Increase the timeout period to some number sufficiently large. Specifically, in the terminal, run
sudo cupsctl Timeout=5400
(sudo
-- as the admin) (cupsctl
-- program controlling the printing system) (Timeout
-- the timeout parameter) (=5400
-- 90 minutes in seconds)
Diagnosis mechanism: (I'm a software developer of nearly 40 years, so that helps here.)
- Open the print queue -- from the Printer menu, bring up the error log -- see nothing of value
- Turn on debug logging -- sudo cupsctl Loglevel=debug
- Attempt to print. Watch for errors...
- Eventually, find message of the form Timeout after 300 seconds
- Search web for that message. Find similar hints, find someone who looks at Timeout CUPS config
- sudo cupsctl Timeout=5400
- 90 minutes should be long enough.
- Retry print job. Success!
Admittedly, a bit involved. Having low-level system server development experience helps.