So I was Masuda method breeding a Pansear and foreign Ditto in the daycare (Pokemon Y); and after each batch of eggs I would save, and hatch a batch until I found the shiny. I finally found a shiny Pansear in the front of a batch (the first egg in the party) and reset to trade that Egg over to my new game in Pokemon X. However, after trading the egg over and hatching it, it turned out the Pansear wasn't shiny anymore. I had checked the rest of the eggs in that batch but no shiny. Any idea why this didn't work? I thought Pokemon were determined after receiving the egg from the daycare. (The reason I reset was to have it back in the egg so when I traded it over to my new game I would be the owner of the shiny when it hatched.)
sumwun is right. Shininess in Gen 6 depends on a combination of the Pokémon’s hidden personality value and the OT’s ID. When you traded the egg, you changed the ID, resulting in a normal Pokémon rather than a shiny one. If you didn’t save after hatching it, then trading it back and hatching it in the original game will make it shiny again.