Mob Spawning Issues 1.14.4

I have recently got a sever but I am getting mob spawning issues. I made a guardian farm, I will get some guardians spawning but after a while they will stop spawning it is the same for my slime farm. the plugins I have are CoreProtect, Essentials, EssentialsSpawn, GriefPrevention, LuckPerms, LWC, SkQuery, Skript and Vault. The server view distance is set to 10 and the mob spawn range is also 10 any help is appreciated.

I had the same issue with my slime farm. In bukkit.yml I changed…

spawn-limits:
monsters: 150

In spigot.yml I changed…

world-settings:
default:
mob-spawn-range: 15

In paper.yml I changed…

world-settings:
default:
per-player-mob-spawns: true

No issues after I made the changes.