Just in case it helps, I've noticed that copy/paste from evernote v7.8 (appstore) to TextEdit (High Sierra), just eats the first (or the last?) empty line of a group of empty lines ( 1 blank line turns into no line, 2 blank into one blank line, 3 blanks into 2, and so on) Maybe this is related to the way Line Ending is managed by EN and other editors.
Same paragraph copied from evernote to MS Word results in an exact copy: no blank lines are missing.