nether not spawning blazes or withers, only zombified pigmen and piglins

[brandude02]

Please paste the output from /usb version below

Name: Uskyblock
Version: 2.9.0
Description: Ultimate Skyblock v2.9.0-7cf840c
Language: en (en)
 State: d=128 r=64 i=5 p=5 n=true awe=false
Server: CraftBukkit 3284a-spigot-3892929-0ab8487 (MC:1.17.1)
State: online=true, bungee=false
-------------------------------------
Vault 1.7.3-b131 (ENABLED)
WorldEdit 7.2.7+9f3e795 (ENABLED)
Worldguard 7.0.7+216b061 (ENABLED)
Mutliverse-Core 4.3.1-b861 (ENABLED)
Multiverse-Portal 4.2.1-b834 (ENABLED)
Multiverse-NetherPortals 4.2.1-b786 (ENABLED)
----------------------------------------

What steps will reproduce the problem?

1. enter the nether
2. place a 15 x 15 square of netherack 22 blocks away
3. wait

If you have any log-files, please paste them to pastebin.com

• server-log: link-to-pastebin

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