resources.zip doesn't load when uploading world to realm

The resources.zip resourcepack doesn't load when uploading a singleplayer world to a realm. See attachment.

 

Steps to reproduce:

1. Have a singleplayer world with a resourcepack in its file (resources.zip)
2. Confirm that the resourcepack loads on singleplayer
3. Upload the world to a realms slot and join the world
4. Observe that the resourcepack does not automatically load