Hi Steven, You might consider getting an inexpensive, but high resolution IR imager, they can be helpful finding moisture, air intrusion, etc. Like Larry mentioned calling out a deficiency is sufficient, but understanding it helps potentially identify further unseen conditions. Someone else mentioned there might be other gaps/openings which is imo likely. The thermal imager makes quick work of checking for ceiling cold spots. It also might show the air flow pattern, or the moisture pattern.
I assume you do not have one, as you did not post any thermal pictures. Seek Thermal Pro is reasonably priced.