From my recent experiments on Test Center, this appears to have been fixed. After making some samurai platemail pieces and removing the mage armor property, I had 5 properties and a full 500 intensity to imbue.so Tina was right, by taking off the Mage Armor your chance at imbuing still is effected by the invisible mage armor that was there.
so not only is it still blocking 1 of the 5 slots (which is as they said it would) it is still counted against the success % like its weight was still there.
so they literally just took off the weight of it, nothing else.
It's great news for me, because I've been getting far more samurai platemail refinements than regular platemail.