Simply put, if I die with Taric and revive thru the guardian angel item, his passive mana per damage buff goes away. I have duplicated this problem several times to my dismay. I was surprised not to find any discussion regarding this problem and after reading a Taric build post that suggested the Guardian angel item, perhaps not everyone will experience the same problem. I'm a forum noob so I apologize for not following standard procedure if there is such a thing.
Attached is a screenshot of a very sad taric with guardian angel and no passive buff.
I'll avoid guardian angel until it is fixed now that i know the cause.