Forest Moon Assault Battle Potential Bug

I was running through Challenge Tier 1 with my successful lineup of Thrawn(L), B1, B2, Magna, and BB8. I got to Phase 4, was hit at the last second by Teebo, but it was unable to bring Magna to his 1 HP threshold. I then progressed through Phase 5, and entered Phase 6 with basically a full health squad.

At this point, I had my Magna use the special ability "Defend", and following the use of that skill, he dropped dead from full protection and health.

Has anyone else experienced this behaviour? Unfortunately, I didn't get any proof of it since it was incredibly unexpected.