Support is good at looking at specific cases, and might be better than banging your head against it.
That said, I usually troubleshoot this kind of thing by looking at an individual lead I think should have been triggered. Then, go to the Activity Log and look for the activity you're hoping to find and make sure it happened. Also make sure there isn't some other filter.
Sheila's suggestion is a good one too- it is a different activity in that case.