Hey Sean, hey Cory (if you’re still floating around out there0,
Have the exact same problem and it’s been driving me nuts. See below:

1:1 resolution comparison of a RAW export. (just the top corner of a 36MP photo from a Nikon D800)
LHS is a JPEG out of Lightroom.
RHS is the same frame in a ProRes 422 HQ video exported at the native resolution of the sensor straight from After Effects.
I thought Dave LaRonde was onto something when he mentioned playing with the project bit depth as I had never changed mine from the default (which of course is just 8bpc) however no amount of purging cache, creating new sessions or whatever seems to affect the outcome.
Interestingly images seem to preview OK in Camera RAW during the initial import, however as soon as the sequence is dropped onto a composition the preview is awful and the fine grain carries through to the final export just as Cory’s initial post did. ????