I just installed Ubuntu 17.10 and my Samsung SCX-4624F Scanner stopped working. What is strange after many tries I scanned one page but couldn't repeat this. After system reboot scanimage -L listed the scanner once and then scanner disappeared.
It turned out that in SANE 1.0.27 released in May 2017 had some USB fix disabled (printer/scanner with USB 2.0 has problems with USB 3.0 port). It is possible to enable the fix with the new environment variable SANE_USB_WORKAROUND=1. After I added it to the .bashrc, SimpleScan started to work correctly.
It turned out that in SANE 1.0.27 released in May 2017 had some USB fix disabled (printer/scanner with USB 2.0 has problems with USB 3.0 port). It is possible to enable the fix with the new environment variable SANE_USB_WORKAROUND=1. After I added it to the .bashrc, SimpleScan started to work correctly.