Invulnerable Kela de Thaym in Round 3

[NemonaMyNameForevermore]

In a normal Kela de Thaym assassination mission today, Kela was invulnerable to damage in the 3rd round with her (i.e. after two bombardment minigames). I left the mission after I realized what was going on, but a little while after I left, my squadmate messaged me and said that Kela became vulnerable again and was able to be killed. I have no idea whether my leaving (I was not the host), or some other factor, led to the return in her vulnerability, as I wasn't there to see it. 

Kela appears to have no health here, but she wasn't taking damage to begin with; she has the hollowed out health bar of any other invulnerable unit. I can't think of anything weird that happened during our assassination attempt that could have caused this. On subsequent Kela attempts, I did not have this problem.

Edited May 6, 2019 by Good_Sword_Of_Clem