All modeled mobs became invisible until server restart.

i think this is modelengines bugs. this bugs are occured for modeled monster.

[14:56:47] [Craft Scheduler Thread - 90 - ModelEngine/WARN]: [ModelEngine] Plugin ModelEngine vR4.0.5 generated an exception while executing task 21
java.util.ConcurrentModificationException: null
	at java.util.TreeMap$PrivateEntryIterator.nextEntry(TreeMap.java:1521) ~[?:?]
	at java.util.TreeMap$ValueIterator.next(TreeMap.java:1566) ~[?:?]
	at com.ticxo.modelengine.core.animation.handler.StateMachineHandler.tickGlobal(StateMachineHandler.java:209) ~[ModelEngine-4.0.6.1.jar:?]
	at com.ticxo.modelengine.core.model.ActiveModelImpl.tick(ActiveModelImpl.java:156) ~[ModelEngine-4.0.6.1.jar:?]
	at com.ticxo.modelengine.core.model.ModeledEntityImpl.tick(ModeledEntityImpl.java:110) ~[ModelEngine-4.0.6.1.jar:?]
	at com.ticxo.modelengine.api.model.ModelUpdater.updateAllModels(ModelUpdater.java:37) ~[ModelEngine-4.0.6.1.jar:?]
	at com.ticxo.modelengine.api.utils.ticker.DualTicker.lambda$queueRepeatingAsyncTask$5(DualTicker.java:57) ~[ModelEngine-4.0.6.1.jar:?]
	at com.ticxo.modelengine.api.utils.ticker.Task.tick(Task.java:25) ~[ModelEngine-4.0.6.1.jar:?]
	at java.util.ArrayList.removeIf(ArrayList.java:1755) ~[?:?]
	at java.util.ArrayList.removeIf(ArrayList.java:1743) ~[?:?]
	at com.ticxo.modelengine.api.utils.ticker.PseudoThread.tick(PseudoThread.java:63) ~[ModelEngine-4.0.6.1.jar:?]
	at org.bukkit.craftbukkit.v1_20_R2.scheduler.CraftTask.run(CraftTask.java:101) ~[purpur-1.20.2.jar:git-Purpur-2095]
	at org.bukkit.craftbukkit.v1_20_R2.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:57) ~[purpur-1.20.2.jar:git-Purpur-2095]
	at com.destroystokyo.paper.ServerSchedulerReportingWrapper.run(ServerSchedulerReportingWrapper.java:22) ~[purpur-1.20.2.jar:?]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) ~[?:?]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) ~[?:?]
	at java.lang.Thread.run(Thread.java:1583) ~[?:?]