Mage-Ring Responder Misses Attack if Reinforced

Unknown

I had a Mage-Ring Responder out (7/7 for 15. Can't attack. If you make a match of 5 or more, it can attack this turn. When ~ attacks, it deals 7 damage to the first enemy creature). On my turn, I see a 5-match, so I make it. The subsequent mana charges up a second Mage-Ring Responder in my hand. At that point I see that the MRR on the board is no longer disabled for a second. Then the MRR in my hand resolves and reinforces, pumping it to 14/8 (it was at 1 health), but then it was once again disabled