Recently I've been using a combination of resource packs to make the textures look how the game looked back before 1.14.
We're making factions so I decided to put a banner on my shield but I realised that it was all low quality once I had put it on the shield so I got a resource pack to fix that
I put it on the realm so people could download the RP to see the shields normally. However since doing that, my friends RP & now my RP don't work on my Realm.
The screenshot shows the "patch" pack below the classic textures pack in the list. That means the classic textures pack will override anything in the patch pack that has the same file name. In order to have the patch pack override the classic textures pack, you need to move it to the top of the list.