I'd love if this could be fixed because it show's the horse as an adult but then reveals it's true form as a foal (I think that's what it's called).
I can confirm this weirdness. Seems like a bug to me because normally you'd be able to speed up the grow process by feeding the horse. Of course not as speedy as it happens in game right now
When you spawn the horse and it's a baby is the intended feature on EMC. You not being able to ride it, is a visual glitch, continue to feed it until you are certain it is an adult, otherwise you'll have to feed it even more.
Feeding a horse 64 sugar will ensure that it works every time. But if that doesn't work, then just wait the 5 minutes for your horses to grow.
Just stop your bickering, its golden apples all the way. I have never had this bug be a problem, just feed and check every few times.
feeding just sugar only raises its happiness level i thought...ive never had this problem from using haybales until fully grown then sugar to make happy