Structures do not spawn mobs after initial generation

Steps to reproduce

1. Create a new world in the current preview.

2. Locate a pillager outpost, monument, or witch hut and teleport there. (Probably applies to nether fortresses too.)

3. /kill @e

4. Stand 30 blocks from the structure and wait.

Expected result

Structure mobs respawn.

Observed result

Structure mobs do not respawn.

Pillagers will not spawn once killed at outposts 

Tried different outposts, extending platform at top, light levels, difficulty, range from outpost. Sat at both for hours trying to resolve. Broke beds and killed all villagers at nearby villages.

Seed : -7512197374154379512

Tested at locations 1704 ~ 488 and 3080 ~ 488