I just noticed this today. I have suddenly stopped taking any sort of damage at all. A Draugr swings his axe at me and I'm not harmed. I jump off a cliff and while I do hear my character yelp and the screen fuzz like it's supposed to, I take,no damage.

No, I checked the console and I'm not running TGM or TIM.

This wouldn't be so bad if it didn't mean it completely makes Potions useless and I spent a LOT of time and gold to make those. And speaking of Potions, I've noticed they've stopped working as well! I'm in a battle at the moment against some Draugr, a Restoration spell in one hand and a Destruction spell in the other, firing off both when I realize that I've run low on Magicka. So I go into my inventory and select a Magicka potion, and while the number I have decreases and the sound plays... the bar isn't filled at all. So, I check my Magic tab with my Active Effects, to see if it's Frostfall telling me I'm cold which effects skills, but no, I'm warm!

Perhaps I need to update my mods? I know Interesting NPCs has an update, which actually ended up solving a problem I had earlier with Sadri where he wouldn't open his store ever and just stayed cooped up in the Cornerclub alongside the Dragonborn captain guy and a bunch of other people.