texturpack didnt load in realm

Texturpack "nature" is active in mainmenu and in my realmsettings. But when I join my Realm, in last second the texturepack switch back to "Standard". When im on my Realm and checking the Realm settings, texturepack nature is actice but not loadet. U can see it even in the settings overlay... It's Grey and Not brown like in the nature Pack.

I need help, so we can finaly build our Realm again.