That's why I use Mordred when missing debuffs has catastrophic results. But that's interesting that you got two Black Propaganda resists in a row. Your soul is Water-element, not Wind, right?
It seems like some Ragnaroks have higher debuff resist than others, and since this stat is invisible you can only find out by trial and error. I went with Mordred for this because the JP wiki mentioned a non-trivial resist rate. For Garuda, I've found that the key to victory is stacking sufficient ATK down (-65%) such that her Overdrives are no longer threatening. That's how I can run with Mordred and not worry about healing or specifically mitigating the Overdrives.