Despite patch 1.3.0.3 claiming to have fixed the abom despawn bug, it continues to persist. The only constant I have found with this bug is that it happens when it tries to cast devour/sacrifice. Sometimes it will go several monos without despawning, and other times I have to resummon it 5 times in a row because it despawns with nothing nearby. Please look into this bug again.
Edit: And before any asks: No, I do not have elixir of hunger activated.