Hi George, I just tested it and saw it with no problems. I loaded the core supplements and the Mythic Adventures source. You need to have the Armored Might Mything Path ability. Once you have that ability assigned to the character, it'll show up on Temporary Bonuses under the "Ability" category.
If you are not already doing so, I recommend using 6.08.00RC6 (which is what I tested).
