New Cow, Chicken, and Pig variants are not appearing in my 5+ year world.

We have a Bedrock Dedicated Server with a world that is almost 6 years old, and it seems as if the new mob variants from the Spring to Life drop are not appearing in my world. We have all the new items: Firefly Bush, Leaf Litter, Bush, etc but none of the new mobs are spawning.

I have tried:

-Killing all cows, chickens, and pigs in the area just incase they were left over from before the update. It didn’t work, I even witnessed new temperate pigs and such spawn in a savanna and taiga biome.

-Going to new generation to see if they spawn in newly generated chunks of the correct biome, they do not. The variants don’t seem to appear at all.

-Going into a separate single player creative world to see if the new mob variants spawn, and they do appear as intended in my single player world.

-Turning off all of my resource packs.

Other things to note:

-We have never had addons or experiments enabled in our world.

-We had a bug when Trial chambers came out that prevented us from earning any loot from Trial Spawners. It has been fixed since, but I thought this info might be helpful since the problem with that was the fact that our world was older than 3+ years.