Basically the name of the topic speaks for itself. Cataclysm loses benefits from XAN rune when druid get CC’d by an elite. To be specific - ice enchanted, the one that drops something on the ground, it explodes and freezes you (might be the same with other types of CC). After that my orange Overpower numbers stopped showing up.
I tried reseting the rune buff while ultimate was still running, but it didn’t work untill I let it completely run out and then reset the whole snapshot.
Might be usefull to pay attention. 