This has happened to me since day one. It's a known bug. Luckily it doesn't really affect anything with regards to magicka regeneration. It's more annoying than anything.
I agree, its a purely cosmetic bug and as such, a minor one. I'm happy to hear that its a known one since, even though there's no urgency, it would be nice if this was to be resolved.
I checked this combo out and it's ok on my game. Any idea what may cause this?
The first time I used this combination, it was ok for me too. Since then, almost every time I use it, I get the bug. Reloading various saves does not help either. I have no idea what's causing it.