E1S12 - The Queen, xp/advancing (this also happened in 1.12)

[Konrad22]

Undead unit kills the queen and advances with that xp

Undead unit kills the queen but does not advance with that xp

So...Elynia apparently does not receive the xp when she is the one killing the Queen. Not fair.

[irydacea]

This might be a side-effect of Elynia's position being altered while the Queen's last breath event is being handled (in the nested begin final cutscene EH). As far as I remember, if a participant changes position before attack events finish processing, it no longer counts as having participated in the fight.