Lightroom Classic will no longer send images to my Canon Pixma PRO-100 printer. I was able to print on 7/15/20 but could not on 8/9/20. The printer prints from other programs on my Apple Mac Book with MacOS 10.15.5
I use the same printer, but on Windows 10. It seems that on my computer the link to the printer is frequently being lost. The solution I have found is to run the My Printer utility that came with the printer and run the repair option. That always seems to fix things for me. I don't know anything at all about the Mac, so that is the only suggestion I would feel comfortable offering.
I was going to ask if back on 7/15/2020 you were on MACOS Catalina, or the prior MACOS, some having upgrades have had print driver issue. But, actually,\ some updates in Catalina may have been an issue.
Print drivers appear to be one set if drivers you can update in MACOS (unlike GPU drivers)
You might want to go to the printer manufactures support page and download fresh new drivers. Remember, their may be multiple ones, one for USB, one fir AirPrint, maybe one for IP.
Oh, and pay attention to what print driver you are selecting, they are not equal in capability.