What was up with that reversed out at first in the first inning?

Was at the game so didn't to hear any commentary on it. Seemed like pitcher lost the fly ball in the air, the hitter stopped running to first figuring it was an easy out, and when the pitcher missed the catch he still got the hitter out at first only for the umps to turn it around and call him safe?

He quit running and didn't run through first base which is taught in little league. It felt like the umps rewarded him for giving up. Any insight?