Same, I just had the same situation : healed myself at 100/100 with an "Improved Heal", then hit spacebar. If the final hit on the opponent is dealed by jade staff, i don't get EM.
As said before, I think the problem is simple : jade staff's healing is done before the damage, then i'm >100, on damage opponent is dealt and game is stopped immediatly before some routine set your score to max(100, score). and i guess you got em if score == 100.
simple way to patch this may be to give EM if final score >= 100 (or max possible score)
i got a similar problem...
playing a flyng staff deck, but in my case I healed me up to 100% health with an improved healing before ending the turn, and I have got no EM anyway... maybe the problem is the last hit with an "healing" weapon....
Edit: Just added some screenshots for this case (100/100, final damages dealt by jade staff, no em)