G-
I am having exactly the same issue. Whenever I go to Spotlight > Instrument Processing > Label Legend Manager absolutely nothing happens at all. No pop up window, no options...
I also have the issue with Spotlight > Utilities > Key to Instrumentation.
Could it have something to do with the setup of the file from the start? I know I didn't used to have this problem a year ago and I am not certain when it creeped up.