Strays do not spawn in the Deep Frozen Ocean biome

Only skeletons spawn in the Deep Frozen Ocean biome.

According to the wiki, strays are supposed to spawn. This was supposedly fixed in a previous version (https://bugs.mojang.com/browse/MC-159821), however it appears to be broken again.

I've tested extended spawning platforms and made sure skylight was directly above the platforms. 

Still no spawning.