[Bug]: Mobs try to spawn but blink in and out of existence 1.12.2

[Miacter]

General Info

• I am running a modpack
• I can reproduce this issue consistently in single-player
• I can reproduce this issue consistently in multi-player
• I have searched for this issue previously and it was either (1) not previously reported, or (2) previously fixed and I am having the same problem.
• I am crashing and can provide my crash report(s)
• I am using the latest version of the mod

Forge version

1.12.2 - 14.23.5.2859

Mod version

1.12.2-1.7.2.

Java version

Java 8 Update 321

Issue Description

When playing on either an online or singleplayer mobs from grimoire of gaia wont spawn even with spawn eggs passed some time playing, instead they will try to spawn appearing for a second a dissapearing in the next as if they were blinking in and out of existence

Additional Information

The mobs used: https://mega.nz/folder/zZJi3BzT#B7sx3viljkPVh7X2E8bYlw

[Mrbysco]

Are you playing in peaceful mode?

[Miacter]

Are you playing in peaceful mode?

nope, in hard