MythicMobs error

[20:38:02 ERROR]: [MythicMobs] [SCHEDULER] Exception thrown whilst executing task
[20:38:02 WARN]: java.util.ConcurrentModificationException
[20:38:02 WARN]: at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:909)
[20:38:02 WARN]: at java.util.ArrayList$Itr.next(ArrayList.java:859)
[20:38:02 WARN]: at io.lumine.xikage.mythicmobs.skills.targeters.LivingInRadiusTargeter.getEntities(LivingInRadiusTargeter.java:26)
[20:38:02 WARN]: at io.lumine.xikage.mythicmobs.skills.AbstractSkill.evaluateTargets(AbstractSkill.java:412)
[20:38:02 WARN]: at io.lumine.xikage.mythicmobs.skills.SkillMechanic.executeSkills(SkillMechanic.java:351)
[20:38:02 WARN]: at io.lumine.xikage.mythicmobs.skills.SkillMechanic.execute(SkillMechanic.java:320)
[20:38:02 WARN]: at io.lumine.xikage.mythicmobs.skills.SkillManager.executeMobTimerSkills(SkillManager.java:337)
[20:38:02 WARN]: at io.lumine.xikage.mythicmobs.skills.SkillManager.runTimerSkills(SkillManager.java:319)
[20:38:02 WARN]: at io.lumine.xikage.mythicmobs.clock.MythicMobsAsyncClock.run(MythicMobsAsyncClock.java:21)
[20:38:02 WARN]: at io.lumine.xikage.mythicmobs.utils.Delegates$RunnableToConsumer.accept(Delegates.java:63)
[20:38:02 WARN]: at io.lumine.xikage.mythicmobs.utils.Schedulers$LumineTask.run(Schedulers.java:164)
[20:38:02 WARN]: at org.bukkit.craftbukkit.v1_15_R1.scheduler.CraftTask.run(CraftTask.java:99)
[20:38:02 WARN]: at org.bukkit.craftbukkit.v1_15_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:54)
[20:38:02 WARN]: at com.destroystokyo.paper.ServerSchedulerReportingWrapper.run(ServerSchedulerReportingWrapper.java:22)
[20:38:02 WARN]: at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
[20:38:02 WARN]: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
[20:38:02 WARN]: at java.lang.Thread.run(Thread.java:748)