Edit for #63 : I tested again today and I was able to scan both in gray and colour (and up to dpi), although I didn't change anything in my hplip configuration (3.20.3) since that comment! So problem mysteriously solved for me... for now.
Edit for #63 : I tested again today and I was able to scan both in gray and colour (and up to dpi), although I didn't change anything in my hplip configuration (3.20.3) since that comment! So problem mysteriously solved for me... for now.