I just tried to convert my Xbox One edition world again. I tried it using the new X console. I am on beta 1.2.5.15 and the world DID convert successfully this time in terms of the terrain. That is the 1st time that has happened for me. Coincidence? I don't know.
There are some issues like the redstone machines are not working properly. Also, I noticed that when I ride a minecart, you can hear footsteps running on whatever surface is underneath the rail lines.
I will try it tomorrow for sure.
I noticed this same thing last night. I was trying to lead a cow over to a pen and it would not climb up a 1 block height difference. It would try to jump a few times and then seem to give up. I noticed the auto save icon going when they would just sit there. Then it would disappear and the cow would seem to not notice I was holding the wheat. When I moved closer to it, suddenly the cow would start moving towards me again.
Every so often the cow would climb the 1 block height but it was very sporadic.
Uploaded my world that is not converting correctly. It is creating terrain that is not in the original. The world was originally made on the XBox One Edition. I also get the Xbox guide crashes after trying to play in the converted world. The screen goes black and the guide button doesn't do anything. Just a normal shutdown does not help. I have to do a full shutdown of my XB1 (holding down the button on the front of the console for 10 seconds).
Receipt number: 2017/10/26/12:59:57-6f8c4465-e0e9-d0c-3-8e34-776c9fa030b3
Hopefully someone else with this issue and an XB1 X can try it. Who knows, maybe it was simply coincidence that my world has finally converted properly. I hadn't tried it in a while so it may not have necessary been the X that made it work.
If it was the X that made it work, then no I would never expect anyone to upgrade ONLY for their world to convert properly.