Darth_Stealth

Use the solution here MC-179858

This is intended 

It's a bug, all structure specific mobs are bugged in worlds created before the current snapshot

On the World select screen, select your world, then click edit at the bottom of the screen then optimise world 

They can only be repaired when using an iron ingot.

That's because the nylium growing through the netherrack helps to hold the structure together thereby making it harder.

It's normal for biomes to sometimes spawn small like this

Previously placed beacon blocks got broken in this snapshot, just mine and replace the beacon block and that will fix the issue

This is an intended feature

Are there any other workstations nearby that it can see? Cause it may be trying to pathfind to it

this is normal

That's why the portal is not spawning, if you want to reset your nether use mcaselector, that way you can keep the chunks that you have portals in while deleting all other chunks.

did you delete parts of your nether to get the new biomes?

You've just gotten unlucky with your seeds

This is happening because you deleted nether chunks that the portals where in 

Are you at least 24 blocks away from the netherrack when trying to spawn them? Also because you are so close to the nether roof mobs can still spawn below you and can take up the mob cap preventing more mobs from spawning

you need to hold shift and left click to do this

Yes I did delete some of the chunks in the save as a test to get the new biomes to spawn, looks like I just have to be more careful about. I have a back up of the save so it's not too much of a problem.

It could just be the seed you're using

That's how 3rd person has always been like