The natural texture pack and skyrim resource pack do not load on realms, it defaults to the normal textures. Other packs such as my custom paintings do seem to work.

I have tested it on Windows 10 as well with the same results. The texture packs are applied but they only show the default. But the world download works fine off of realms.

I have cleared the cache, even deleted and reinstalled. It doesn't work for new worlds either.