Can also confirm the same problem with SCX-3400 model. Printing and scanning worked in all versions before 17.10, and scanning stopped working since then. I also have Debian Testing at home - it doesn't have this problem at all.
I believe this is related to libsane (v1.0.25-4) being renamed to libsane1 (v1.0.27-1) and then maybe something more have changed between these versions. Note that 1.0.27 is actually still tagged as experimental.
Can also confirm that setting SANE_USB_WORKAROUND variable fixes the problem, however it is not a nice workaround and things should just work out of the box.
Can also confirm the same problem with SCX-3400 model. Printing and scanning worked in all versions before 17.10, and scanning stopped working since then. I also have Debian Testing at home - it doesn't have this problem at all.
I believe this is related to libsane (v1.0.25-4) being renamed to libsane1 (v1.0.27-1) and then maybe something more have changed between these versions. Note that 1.0.27 is actually still tagged as experimental.
Can also confirm that setting SANE_USB_WORKAROUND variable fixes the problem, however it is not a nice workaround and things should just work out of the box.