Custom resource pack makes inventories lag / isn't downloaded correctly.

Trying to get a custom resource pack to work on our server. These are our current circumstances: When using the resource pack in a user client it works perfectly fine, no inventory lag and no other weird stuff. When using the resource pack as a server resource pack inventories aren't processed correctly; they only update when you open a chest (the whole inventory, including armor slots). The file attached shows how it would look in the server.properties ini. Any help would be appreciated.