Since updating to portage 2.0.37 when I do emerge -pu world all packages that should be updated are displayed as new. This only happens with "world", when I do for instance emerge -p gnome, the necessary packages are displayed right with "U"
Actually, it happens if you do emerge -up gnome as well. All, the packages will be listed as N as opposed to U. If you do emerge -p gnome, then all the packages are listed as U as you described. To sum up, the problem arises when you do an emerge --update whether you specify world or a specific pacakge.
*** This bug has been marked as a duplicate of 8128 ***