Floodlight Piggybacked Dynamic Tags Not Firing

I have a Floodlight with a half dozen partners' tags piggybacking it (as Dynamic Tags). The Floodlight itself is deployed through a tag manager. I can see the Floodlight firing as well as conversion reporting, but I can't see any of the Dynamic Tags firing.

• The tags are all SSL-compliant.
• When tested, all tags work on their own. But not when piggybacked.
• One of the partners claims they're seeing reporting on their end (which is bananas to me since I can't see their tag firing; they could be mistaken).
• DCM Support couldn't find anything wrong with our implementation. They concluded "something" on our site must be blocking the tags from firing. Not sure what that could be.
• We recently switched our Floodlights over from iFrame style to Global Tag style. Some of the partners' tags were already implemented before the changeover and some were added after.
• As far as the new format, we have implemented both the Global and the Event snippets. Like I said, I can see them firing and we've been receiving consistent reporting since the changeover.

I'm at a loss for why this is happening. Any ideas?