Just as the fighters were scheduled to make the walkout for the UFC Vegas 107 main event at the UFC Apex in Las Vegas on Saturday, the headlining fight was  abruptly canceled .  No. 4 ranked Erin Blanchfield was pitted against No. 5 ranked Maycee Barber in a fight that could have determined the next title challenger, but the two never stepped foot inside the octagon.  As she was about to make her way to the cage, Barber had a medical issue and wasn’t cleared to fight.