Was Erika Thompson actually the source of the PapaD intelligence, and Downer was the cover?
The Downer meeting wasn't until May 10th, but the Mueller reports the information from PapaD came on May 6th.
That would indicated Erika (also an IC asset) was the source, not Downer in the pub.
It would explain why Downer denies it.
OR, this is a lie by Mueller to get Downer off the hook.