Samsung CLX-6260 Duplex Printing only works with generic driver, but cannot print in mono

[keylevel]

The post here showed how to use the generic postscript driver to restore duplex printing to the CLX-6260 under Catalina. That also works for me, but there appears to be no option to allow mono printing to be selected.

There are now HP Drivers for Catalina ( see here ), but these do not install properly as the driver has a "notarization issue" that results in security warnings during installation. This is noted at the bottom of the download page - "Notarization issue can occur with the driver. Refer to the following document 'c06550177'", but there is no link to that document and "search" does not find it either. I think I have managed to get the driver to install (using the Security settings), but it then fails to print with a "filter error" being shown in the printer queue.

Has anyone managed to get this printer to print double-sided in mono?

[henkhb]

Same issue here. Really no solution from HP? 

Air Print is very limited and slow in my case, so I need a working driver.