Ubuntu 20.04 non vede più scanner Samsung scx-4216f

Buongiorno a tutti, dopo gli ultimi aggiornamenti (ipotizzo dal kernel 5.4.0.48 ?) la stampante multifunzione Samsung scx-4216f collegata via usb non viene più vista come scanner. Il comando lsusb mi fa vedere la stampante/scanner:

lsusb
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 008: ID 04e8:3409 Samsung Electronics Co., Ltd SCX-4216F Scanner
Bus 005 Device 002: ID 046d:c047 Logitech, Inc. Laser Mouse M-UAL120
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 002: ID 04f2:b008 Chicony Electronics Co., Ltd USB 2.0 Camera
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

Ma sane-find-scanner (anche se lanciato da root) non lo vede

 # sane-find-scanner will now attempt to detect your scanner. If the
 # result is different from what you expected, first make sure your
 # scanner is powered up and properly connected to your computer.

 # No SCSI scanners found. If you expected something different, make sure that
 # you have loaded a kernel SCSI driver for your SCSI adapter.

 # No USB scanners found. If you expected something different, make sure that
 # you have loaded a kernel driver for your USB host controller and have setup
 # the USB system correctly. See man sane-usb for details.

 # Not checking for parallel port scanners.

 # Most Scanners connected to the parallel port or other proprietary ports
 # can't be detected by this program.

Come stampante funziona, anche se ogni tanto segnala errori di connessione che prima non succedevano, sembra un problema nella gestione delle connessioni via usb

Qualche suggerimento? Grazie, Gianpiero.