Mobs do not spawn in structures

Steps to reproduce

1. Create a world with default settings and creative mode.

2. /setblock ~~~ portal

3. /locate structure fortress

4. Teleport or travel to the fortress and explore it.

Expected result

Fortress mobs spawn in the fortress.

Observed result

Fortress mobs do not spawn.

(I’m posting this second time) while  playing Minecraft Bedrock on the latest preview version(1.20.60.23 preview) on realms, I discovered that mobs do not spawn in nether fortresses.  All mobs like piglins and hoglins spawn around the fortress or in the fortress, but I spent half an hour in different fortresses and no mob except blaze from the spawner didn’t spawn (this problem also occurs on singleplayer worlds - I checked on other world) also i tried change from hard to easy or peacefull and try like reset the spawn of mobs and it didn’t change nothing 

on 1.20.60.22 preview mobs normally spawned. (After a two days no mobs like wither skeletons spawn in nether fortress, only piglins ang hoglins spawn around nether fortress still)