Very long time AE/PPro user but I don't remember coming across this issue before:
I have a sequence in PPro that has 3 dynamic linked AE comps in it. The comps are all in the same AE file. I render the entire timeline in PPro and the indicators are green for all of the AE comp sections and appear to be rendered correctly with motion blur and camera DOF etc.
I export the sequence to H264 at high data rate (a modified Vimeo export preset - 1080P) and select to use previews. However, on encoding, it appears that previews are NOT being used and AE is obviously rendering the comps again (as the export takes about an hour as opposed to about a minute if the previews were being used).
Anyone else seen this issue? Wondering if the use previews switch is broken in the current release?
It works here. My guess is something else is slowing things down.