I've checked to make sure, but it seems like not all set bonuses gets applied when taking an ouro mission of lower level.
While I could go behind if it were on powers deactivated, it doesn't seem to be the case.
To check, I completed the set Efficacy adaptor on Stamina, which as far as I remember is one of the base power, and none of bonuses were applied.
The only one I could see applied was "numina convalescence."
As of this posting, the sets I've got:
5 Rooting grasp on Crush.
6 Neuronic shutdown on gravity distortion.
4 Ghost widow's embrace on Gravity distortion field.
2 Stagger on Wormhole.
2 commanding presence on singularity.
4 Impervium armor on steamy mist, plus 2 Impervious skin.
6 Touch of lady gray on Freezing rain.
2 Dampened Spirits on Hurricane.
6 Efficacy adaptor on stamina.
2 Numina's convalescence on Health.
I'm not sure if that is intended, or if it's a bug.
If it is intended, it certainly is not clear how or why it is happening, and can make lower level scaled missions difficult to plan, as there seem to be no way to either see, or predict, which things will get applied or not.