Just in case, one more information : I performed a test with a wireless scanner (Brother MFC-J6720DW). It was properly detected with "scanimage -L". So the problem seems to be specific to USB connected scanner.
Just in case, one more information : I performed a test with a wireless scanner (Brother MFC-J6720DW). It was properly detected with "scanimage -L". So the problem seems to be specific to USB connected scanner.