Hi
I have hade a simular problem because of to long file paths. Some of the songs in a Album did not show up. Tagscanner, my favorite tool, have a feature that can restrict the length of a file. It simple renames all paths to shorter names.

You could use Tagscanner,, or a simular tool,,, to rename the songs in one of your problematic Albums. Then clear and rescan. If the songs shows up,,, well there is a reason to belive that you found the problem.

//lg