Desert rabbits were the wrong color, but now they are missing

Good news! I found some rabbits! Except they spawned in a River biome not a desert and they were the standard brown color. I might be wrong, but I don't think they are supposed to spawn in River biomes? Also I still cannot find any rabbits anywhere else. Will keep looking. (see pic - rabbits)

seed: -8300275442758179407
xyz: 1485 64 -134

Andre Pugliese pointed out (MC-126859) that polar bears aren't spawning on ice plains either.

I'm going to see what animals I can find.

So. I have new information.

It looks like passive and neutral mobs that have no biome specified in their spawning criteria are spawning fine (i.e. pigs, cows, chickens, spiders, etc.). But if there is a biome specified they aren't spawning (polar bears, wolves, rabbits, etc.). Now I did see a polar bear on a frozen ocean. And I saw some rabbits in a river biome, so I think anything that spawns in a water biome is still spawning correctly since that was what the programmers have been working on in these snapshots.

seed: -8300275442758179407

spawning normally: bats, chickens, cows, mooshrooms, pigs, sheep, squid, villagers, fish (all types), endermen, spiders, zombie pigmen, cave spiders

not spawning in correct biome: ocelot (saw 0), parrot (saw 0), rabbit (saw 2 in a river biome), llama (saw 0), polar bear (saw 1 on a cold or frozen ocean), wolf (saw 0)

Horses are spawning normally, but I haven't seen any donkeys. I'm guessing the reason is donkeys are variations on horses. I also didn't seen any skeleton horses, but they spawn a lot less often so it's possible I missed them, or it's possible they aren't spawning because they are also horse variations.

This is still an issue in 18w20c. This time when I went looking for things the only mobs I couldn't find were: ocelots, parrots, and rabbits.*

*I found white rabbits in the cold taiga and ice plains, but could not find any other color in any other biome.

However, all the mobs seem to be spawning in patches or super slowly. I can wander around an area in the day and not see any mobs at all. Most of the time once night come the hostile mobs spawn and then the passive and neutral mobs will spawn too. But I've been wandering around at night and gone a long way without seeing any mobs at all. Also the biome specific mobs (llamas, polar bears, pufferfish, etc.) are always the last ones to spawn.

I'm wondering if the slow spawning has to do with MC-129492, in which something is eating up memory super fast. Because it seems the more memory gets eaten the less mobs spawn or vice versa. 

Confirmed in 18w22a.

Still can't find any golden rabbits in the desert. I have found white rabbits in snowy areas, but no black and white rabbits. I found brown rabbits in taiga/cold taiga areas, but only the standard brown color. I haven't found any other rabbits anywhere else.

Also, while the parrots are back, I still can't find any ocelots in the jungles (MC-127156).

This part is still an issue as well: "However, all the mobs seem to be spawning in patches or super slowly. I can wander around an area in the day and not see any mobs at all. Most of the time once night come the hostile mobs spawn and then the passive and neutral mobs will spawn too. But I've been wandering around at night and gone a long way without seeing any mobs at all. Also the biome specific mobs (llamas, polar bears, pufferfish, etc.) are always the last ones to spawn."