A global change that was made to summoners a while back was that no summoner that pulls from a kingdom or troop type pool can summon themselves. The same applies to, say, Goblin King or Hyndla Frostcrown and a ton of other things with the same spell description, because it is just a global rule for how these types of summons work.
Found it, version 3.0:
If Vanya could summon Vanya, it would most likely be considered a bug.