Hello there.
I have a different scanner (MG6250) but it too stopped working after High Sierra.
Trying the obvious things (updating drivers and so on) did not solve the problem.
I noticed however sometimes, when i tried to scan with the scan button to my iMac, the program MP Navigator crashed.
After download and install version 5.0.4 there still was no solution, but...
I got another crash window and reading that it stated MP navigator crashed on version 5.0........3 ?!?!
A new run of the installer and a manual start of MP navigator showed me the I still launched the 5.0.3 version, not the one I tried to install already 2 times....
So it seems for some reason the 5.0.4 installer does not remove the 5.0.3 version as it should.
After some read up here and there I tried this;
Remove the MP navigator and its 'Opener' from the Canon Utilities folder in the Programs folder.
Run the 5.0.4 installer again.
Try to launch it from Programs/Canon Utilities >>> now check "about MP navigator' and it should read 5.0.4 instead of 5.0.3
Then reboot your Mac and once booted try to scan to your mac using the scan button in your scanner(multifunctional)
For me this worked.🙂