Enemies overcoming Spell Conditions even after failed save Bug or not?

[chaotic_intent]

I've had a few instances, most recently a fight with Dolor in Act 3 , where I used a save or suck spell (Phantasmal Killer in this case) and it initially hits (enemy fails save). Next turn comes around and they fail their save again but they overcome the condition anyway so they weren't frightened nor did they take the 4d10 damage. Not sure if that's a bug (seems like it should be) or if it's scripted because the guy is like a "boss" enemy (I guess lol) so save or suck spells aren't supposed to work on them or something. I'm pretty sure it's happened a few times throughout the game for me but it just extra annoyed me this time cause I've been looking forward to using Phantasmal Killer and was pretty stoked that the guy failed his save initially. Maybe the log just put completely incorrect info and the guy succeeded the save? Anyone else run into anything similar or can provide any insight here?