There was a good discussion on this earlier this year. As I understand yhe issue you describe:
1) you can manually add the category name, but you don't get the plus(+) sign to 'populate' the adress field
2) you can hit one of the adressee links to the contact list and categories works as it should.
Attachment 289039Attachment 288934
If that's correct, it appears to be an issue related to upgrading as opposed to a new install. I've been running WLM 2012 since it was released without issue, but I'm a bit of a clean system freak. As soon as one issue crops up I do a fresh base install of the troubling application.
Ty a repair of WLM.
WinKey + R brings up the run dialog; type the following in the box to bring up the 'install' dialog
wlarp.exe
select repair
Attachment 288936
This was not effective in testing done earlier this year but things change.
I never did write the instructions, so I'll have to work through them again if you can't life without this feature.
The basic steps are:
backup your user data
uninstall WLM
rename folders associated with WLM (programs and user files)
CClean your system (WLM related registry entries)
Download WLM 2012
install from local msi/exe
reboot
rename user folders associated with WLM
copy original renamed user folders back to original name(s)
start WLM and test
I seem to recal losing contact information, but I have plenty of backups. You might also lose any filters (new mail moved to specific folder upon arrival, etc.) if you built any.
Your mail servers and eMail is unaffected.