That is no glitch.. Shininess is partially based on the ID and SID of the hatcher. As soon as you changed the games, the Pokemon failed to be shiny. Different IDs/SIDs.
RESET AND TRADE BACK!!
<333
i.e. Jeremy is wrong. Shiny eggs only hatch shiny in a certain game. Not in every person's game.
f my life.. i'm gonna cry right now :( :(
i just rngd 6 beautiful shiny eggs in my platinum and traded them to my diamond.. and then hatched them.. the sprite when hatched showed up as shiny but then when i checked the pokemon in their summaries, they weren't shiny.. no one told me that you had to HATCH the fricken egg on the same game that u RNGd it.....
4 hours of work gone down the goddamn drain.... *sob*