Yes it does. If I drag the note from a Local notebook in Legacy to a Synchronised notebook in Legacy, then view the (now synchronised) note using Evernote 10.57.5 - the metadata is fully intact (which is GREAT!) BUT, instead of getting "Missing Plugin" in Legacy, I get "Untitled Attachment" instead.
In Legacy, I can see the attachment using Presentation Mode - but 10.57.5 doesn't let see see or download the attachment at all.
using ENEX export & import, I can see the attachment, but the metadata (date created & updated) is lost....
NOTE: this ONLY seems to happen with .pdf's - everything else seems to work.