Joshua McKay

This is also working as it's supposed to I think. You need to get an advancement first for them to show up. Give yourself cobblestone or blackstone to get Stone Age and some will show, or go to the Nether to show the Nether advancements, which are the new 1.16 ones. Also, advancements don't get disabled in Java. You can use cheats and creative and you'll get them still.

I don't know much about the biome generation changes put in place but from what I'm seeing biome generation is broken again. I've looked for a newly reported issue on this but haven't found one. I'm finding very small biomes, like this tiny Basalt Deltas and this pretty small Warped Forest. I can't find the tiny Basalt Deltas anymore but here's the world seed. -5600731631520659808 The Warped Forest coordinates are in the pictures.

The final picture is a back view from the second picture.

I'm assuming you're referring to the Soul Speed Iron Boots they give? Either way, I've had this happen as well sometimes.