Twisted Fate Seraph's Embrace Interaction

When tf has seraph's embrace it should give him nearly half his max mana after he uses his ability, but it doesn't actually do that. When he starts shuffling the cards he gains the 20 mana as intended, but once he throws out x card he immediatly loses all mana again, thus rendering seraph's embrace nearly completely usesless (apart from the initial 40 mana at start of comabt..)