John Collins

With the changing of Achievements to the new Advancements system in the latest versions of Minecraft, I am unable to confirm if the problem still occors, since Achievements no longer exist. Loading the same worlds in a previous version where Achievements still exist causes them to reset, but this is very likely due to a lack of data on Achievements to fall back on.

As for Advancements, they appear to be stable. I have not have any Advancements reset so far.

I just had three horses vanish in 1.12 when I re-entered the chunk they were in. Two were tamed, armoured, named horses, and one (their offspring) was untamed.

-My world is local singleplayer, updated to 1.12. The horses were still there when I first loaded my world in 1.12.
-The horses' pen is surrounded by wooden fence on three sides, and a cobblestone wall on the fourth side.
-I searched the land within a 50-block radius of the horse pen, but there was no sign of my horses.
-There is no evidence they suffocated. No drops were present in or around the pen.
-I have pigs, sheep, dogs, cats, etc. in the same chunk, and they were all there (minus a sheep that suffocated, as evidence by its drops...)
-I tried exiting and re-loading the world, but the three horses were still missing. (The horse I rode back on was still there.)
-Not sure if this is relevant, but the last thing I did in another chunk (animal-related) was tame and saddle another horse.

About a month ago, I loaded up a Minecraft world I hadn't loaded yet with the new launcher. Unlike my other re-loaded worlds, almost all of my achievements were still there, minus "The End?" and on. (I had already beaten the Ender Dragon in that world a long time ago.) I am unsure if the bug is fixed, or if this was simply a random occurance.

-This world that I loaded was my oldest world (pre-horse update), but I have re-visited it in more recent versions. (post-flower update)
-I re-visited the End, and it was as I had left it, with the dragon gone and the exit portal there. I re-got the achievements for going there.

None of my other world-based achievements have disappeared since I've re-gotten them after using the new launcher. It is possible the achievement-vanishing bug was on my end, but unfortunately I have no way of confirming this.

Regardless, thank you all for your efforts. 🙂

Yes, I did.