Time: Any
Frequency: Always
World Name: Balmung
Character Name: Echru'a Kurana
Class/Level: Lvl 50 WAR
Party or Solo: Either
In-Game Time: Any
Steps:
1. Visit any retainer summoning bell regardless of the area.
2. Attempt to summon either retainer (they have never successfully been summoned at all)
3. The game crashes immediately before the retainer appears.

I've also dismissed and rehired retainers to see if that would fix the issue, however it hasn't made any difference.