While trying to update a pack on my Realm, I incremented the version number and left the UUID the same. The game read it as a new update, and overwrote the other pack in my single player world. On the Realm, in the resources, it showed that it was the 1.3 pack, but when I left the settings page nothing uploaded. I looked on the Realm, and it was still the 1.2 pack. I then went back into the settings page and deactivated the pack and backed out so it would save. It saved the settings this time, and when I went back in there was no pack, so I reattached the 1.3 pack and backed out. This time it uploaded with no problems. Checked on the Realm and it was the 1.3 pack. so I did get it to update without pulling the world down, but in order to do it, I had to remove the pack first.

If possible, this is the behavior I would expect:

I have pack 1.0.0 on my realm

I install pack 1.1.0 to my machine with updates to the version, but the same UUID

I open the Realm settings, and verify that the Realm settings show 1.1.0 as the current pack

I leave Realm setting or click play world At this point the new pack is uploaded, therefor closing the Realm, and if version number is increased, it overwrites the old version

The realm reopens, and as users join, they are prompted to redownload the pack to overwrite the pack they have on their local machines cache Realm pack is updated