There's one weird bug in Object-Trigedit, seems that the DG code there can't see INVISIBLE or HIDDEN mobs.
You can test that by having a scripted object doing this:
%force% mobname say ciao
If the mob is INVISIBLE or HIDDEN the %force% command won't do anything.
Can any of the coders check what's wrong in the code and let me know if it's easy fixable?
Are you sure it isn't because the mob is over level 50?