What happens, if you put this into a weight reduction backpack? Hm.

I've had this too, I'm not sure what causes it but as long as this is after the item tweaker api in the load order it should work. When it hasn't worked for me restarting has fixed it some times.

I seem to have a problem where I can't loot any of the jewellery, character just kneels down and has an infinite progress bar without actually picking anything up.

very interesting :)
hehe i have 1 full duffle bag of rings etc so far