Exactly same, with macOS 10.14.6 scanner (WC 6515) stopped responding, with another Mac running macOS 10.4.5 works fine.
Hi, just want to inform that the update from Mac OS 10.14.5 to 10.14.6 makes problem with finding the scanner of the 6515 work center. (Air Print)
First I had PDF files where all scanned sides where destroyed, so I downloaded the latest driver from xerox. After installing that the scanner could not be opened. The windwos shows a massage, "open Scanner". Scanner does not answer.
Did printer reset, new firmware, printer settings reset, Ram Parameter Reset, nothing worked
I can compare with an other Mac, 10.14.5, there everything works fine. Now I will restore with time machine to the previous version. Think that is an update bug by Mac.