Texture pack will only partially load on an existing realm

I downloaded "Medieval Texture Pack" and it will only partially load on my existing realm that my friends play on. The same goes for the "Greek Mythology Mash-up" pack. I downloaded the world as a copy and reset the world. Played on the "new" realm and the pack worked but when I chose "replace world" and put the copy back in, the texture pack only partially worked still.