Sync should correct that though.
If you are still having issues then disconnect the light that is synced from the transformer and then turn the light on that isn't synced to the color that all the others are set to by cycling the power, hook everything back up and try it then.
Is the light actually out of sync but still working correctly? I ask because when these lights begin to fail they either get stuck on one color or lose the ability to display one or more colors. These lights are notorious for failure so it wouldn't surprise me if the light is going bad.