Omens Not Deploying Properly

I've noticed while doing endgame activities in POE2 that it seems sometimes the omens (Resurgence & Amelioration) aren't deploying as they should or incorrectly. Recently I have been in a breach and pretty much got one-shot by an enemy but instead of using the Amelioration it used up the Resurgence? It's happened this way more often than anything else but there have also been a number of times where none would deploy at all and I can assure you it was not during a Pinnacle boss fight.

Didn't know if anyone else was experiencing this issue or just me perhaps!

Thanks!

Only one Omen can be triggered per combat area, so it is normal that only one of them worked.

Oh okay that explains a lot. Does combat area specifically mean the area or location or is it based on which enemy I'm engaged with? Just because I have had both deploy but, it very well could've been with a new enemy or perhaps I might've just been on the border to a new "area" as it's defined.