When using graphics/sane-backends from ports, my scanner will only ever get me a completely black image.
This issue has persisted since I got the scanner years ago. When I got the scanner I downloaded sane-backends manually and built it from source, which according to the newest ChangeLogs/* file should be 1.0.27.
When compiling that one from source directly, back then and now, I can use the scanner.
Report it upstream. I don't have that scanner.
Better if you can bisect it and find the commit that broke it.
That is not caused by any breakage in newer versions -- that was an issue with t he port back when that version was shipped as a package too.
So it likely is some missing dependency that gets picked up when building in an unclean environment that makes it work.
I'll investigate it, once I find some time :)