So you are using Apples Airprint software to scan to your Mac instead of doing a direct scan?
I assume then you did a Mac update and that is what broke the scan option?
This guy says that if you disable IPv6 on the printer it may work again (He has a Canon)
And his reference is this guy (He has an HP)
Seems to be a pretty common failure.
So open EWS and login as admin (admin/1111)
Go to Properties > Connectivity > Ethernet
Click Edit here
Change Dual Stack to IPv4 and click OK
It should tell you to reboot, and according to most other people with the issue, it should fix it. Hopefully you don't use IPv6 though.
Type of scan (email-FTP-SMB-TWAIN-HTTP)
OS of device scanned to (You list 2 different Mac OS versions in your post)
Did it work and then stop or has it never worked?
Does scan fail to everything or does some scanning work to some things?
Image Capture @ macOS 10.14.1 Mojave