/mm mobs spawn Command Not Spawning Properly

Hello, I have it set up so the console runs the command /mm mobs spawn MythicMob 1 the_end,-38,45,0 every week, the problem is that the mob doesn't spawn unless a player is in the world near its spawn point.

I've even tried using plugins that keep certain chunks loaded no matter what, but the mob still doesn't spawn unless someone is nearby. Is there a fix for this?