Mobs specific to structures aren't spawning in their structures

Can confirm in 21w40a.

Seed: -4910909757403150144
Coords: -474 76 -2878

^{Edited to enclose seed and coords in code.}

I have the same issue in newest snapshot. I noted the coords of an ocean monument in 1.17 with datapack, and I know it generated the chunk at that time, and when I went there the other day there were no Guardians, only Elder Guardians.

I tested this on two newly created worlds in 21w40a - I have screenshots of two pillager outposts with no pillagers spawning and no iron golums in cages.

Can confirm in 21w41a.

Seed: -4910909757403150144
Coords: -13 73 -2979

The world is different due to the new random number generator implemented in this snapshot.

In 21w41a, I found a golem at an outpost, and elder guardians at a monument, but no pillagers or guardians.

Yes still happening in 21w41a

This may be unrelated, but pandas seem to not spawn as well.

That's correct, pandas aren't spawning either. See this bugreport: MC-236689

Are Bastions not working properly aswell? Cause i have a sneaking suspicion only the initially placed piglin brutes appear there but no additional ones spawn after you kill all of them.

Or maybe it's just my luck.

Piglin brutes only spawn once. Quoting the wiki: “A small number of piglin brutes spawn in bastion remnants only upon generation and in some rooms.”

What the heck? I could have sworn i see Piglin brutes re-appearing in same bastion i visited several times and cleared on 1.16 (It was my source of blackstone bricks)

Interesting. Maybe normal piglins respawn but not brutes and you’re misremembering? I really don’t know.

Hmm maybe.

Can confirm for 21w42a 

In seed 5262073205950916288 at coordinates 201/-2276 in 21w42a, I found a pillager outpost with a golem but no pillagers... I hope it can help.

A patch to fix it: https://github.com/Linkin-Lab-Server/FIX-MC-237986

This is probably caused by reccurence of MC-184740

But this happen for new worlds as well.

It's strange that Elder guardians are spawning, maybe because they come with the structure when the world generates? Eitherway, a very important bug that still is not assigned...

Elder Guardians don't spawn post-generation

Can confirm for 21w43a, for the following structures and mobs:

• Ocean Monuments (Guardians do not spawn, Elder Guardians do)

• Pillager Outposts (Pillagers do not spawn, Iron Golems might, Pillagers do spawn in raids, I'm not sure if patrols still occur)

What DOES work:

• Bastion Remnants (Both Piglins and Piglin Brutes spawn, as well as Hoglins in Hoglin stables)

• End (The Ender Dragon spawns, as do the pillars with Ender Crystals)

• End Cities (Shulkers spawn)

• Fortresses (Zombified Piglins, Wither Skeletons, Blazes, and Magma Cubes all spawn)

• Igloos with Basements (both a Villager and a Zombie Villager spawn)

• Mansions (Vindicators and Evokers both spawn)

• Ocean Ruins (Drowned spawn)

• Raids (Vindicators, Evokers, Witches, Pillagers, and Ravagers can all spawn)

• Swamp Huts (Both a Witch and a black Cat spawn)

• Villages (Villagers spawn)

Grey Areas:

• Shipwrecks (I could swear Drowned spawn here before, but I might be mistaken)

The initial witch + black cat do spawn in witch huts as they are part of initial generation. The witches that should continue to spawn in witch huts as part of normal mob spawning cycles however do NOT spawn. Fortresses might only be spawning fortress specific enemies due to the rule about fortress enemies spawning on nether brick anywhere in the nether, while the fortress bounding box itself isn't doing anything. It would be good to verify which is occurring.

Also while not really caused by bug but still somewhat related. Would it be possible that something is done about Dark Forests aswell?

No hostile mobs are able to spawn during daytime there anymore because the light level is not low enough anymore.

Which is a shame the concept of Dark Forest being unique and dangerous having mob spawn even during daytime was pretty much erased with the new light level changes.

@Martin The changes to spawning based on light are only for block light, not sun light. Dark forests should still be able to spawn monsters during the day, however they are less likely to do so given the huge amount of caves underground basically filling up the mob cap. With so many more places for mobs to spawn, mobs are much less likely to spawn in any given spot. There definitely should be some tweaks to the mob cap, but also this is most definitely unrelated to this specific ticket.

@Peter Rabbit

I only know that so far Dark Forests are pretty much devoid of any hostile mobs during daytime for one reason or another. Personally i never encountered a single hostile mob so far in Dark Forests during daytime. (During night time they spawn normally there and everywhere else so not 100% sure if this is cave size related.)

While in 1.16.5 they were pretty plentiful there.

But yea you are right that's a talk for a different topic.

Ok yea something is definatley wrong with Dark Forests.

Mobs do not spawn under the canopies during daytime anymore on the snapshots.

This is not a mob cap issue cause i made sure nothing else spawned under me.

It acts like Sky Light level counts and not just Block Light and Sky Light cannot ever reach 0 in Dark Forests probably why absolutely no hostile mobs are ever able to spawn there during daytime.

Areas below sky light level 7 don't seem to work when spawning enemies. It must be Sky Light 0 for enemies to properly spawn now.

Dark forests work fine on 1.16.5 and 1.17.1 for example. Hostiles spawn properly in Dark Forests during day.

So if the light level changes for mob spawning supposed to by only for Block Light than its clearly not working as intended. Not sure if i should make a separate report or does this qualify as part of this bug report?