Found a bug, and a possible way to close the quest.
BUG: I had stored my witches eye in a bag, so when I crafted the potion it stored the potion back in my bag. Then when I fed both of the cows it didn't remove the potion from my bag but still turned them both back human. (quest didn't close however)
Closing Quest: To close the quest, I had to drop my second potion on the ground and feed the cows 1 at a time. It seems something about feeding both at the same time caused the quest log to bug out and not "CLOSE" for me. After reloading and doing this I was able to get the quest to close.