Thanks, Mark. In the elegance stakes, that solution scores zero, I'm afraid! Fortunately, by updating MP Navigator to v4.0.5 and reinstalling the IJ Network Tool in its latest version, all problems with my MG 6150 have been overcome. Took me a couple of hours to sort that out and I would have hoped for an auto-update from Canon, to be honest, but the job's done, thankfully. Hopefully this might help other sufferers.
Just spent the last 2 hours of my life on this problem, mostly reading through the whole thread. I have a MP560 and none of the work arounds helped. Not Preview, Image Scanner, MP 3.1 or 4.0 or any other. In the end I used a simple solution to get the work done I needed to do today and that was simply inserting a thumb drive in the USB port of the scanner and scanning directly to it then moving the thumb drive to my Mac. Bottom line I too am incredulous that corporations are willing to force customers to buy new technology by not supporting old equipment. Sadly our anger clearly means nothing to these corporations as we can see that Apple repeatedly pulls stunts like this and we all keep buying because at the end of the day the new technology ultimately wins out.
Maybe we'll get lucky and California or the EU will pass a law requiring tech companies to support products for a minimum time say a decade or two.
09/26/2023: New firmware updates are available.
08/18/2023: Canon EOS R5 C training series is released.
07/31/2023: New firmware updates are available.
05/31/2023: New firmware updates are available.
05/18/2023: New firmware updates are available.
03/30/2023: New firmware updates are available.