No mobs spawning in pillager outpost

What I expected to happen was...:
Pillager outpost should spawn pillagers and other creatures.

What actually happened was...:
When i arrive at the outpost there was nothing. No mobs is spawning. 'Bad Omen' cannot be triggered. Both dedicated server and singleplayer world will reproduce this bug.

Steps to Reproduce:
There is just nothing in pillager outpost, which i consider it a bug. There is a decent probability that swamp hut also has the same issue (not spawning witch).