MM Lore-NBT Error

[21:14:02] [Server thread/INFO]: pentlock issued server command: /mm i get Dev_Copper_Chestplate
[21:14:02] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'mm' in plugin MythicMobs v5.0.0-SNAPSHOT-d4b3678c
	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:47) ~[patched_1.17.jar:git-Purpur-1231]
	at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:172) ~[patched_1.17.jar:git-Purpur-1231]
	at org.bukkit.craftbukkit.v1_17_R1.CraftServer.dispatchCommand(CraftServer.java:821) ~[patched_1.17.jar:git-Purpur-1231]
	at net.minecraft.server.network.ServerGamePacketListenerImpl.handleCommand(ServerGamePacketListenerImpl.java:2315) ~[?:?]
	at net.minecraft.server.network.ServerGamePacketListenerImpl.handleChat(ServerGamePacketListenerImpl.java:2126) ~[?:?]
	at net.minecraft.server.network.ServerGamePacketListenerImpl.handleChat(ServerGamePacketListenerImpl.java:2107) ~[?:?]
	at net.minecraft.network.protocol.game.ServerboundChatPacket.handle(ServerboundChatPacket.java:46) ~[?:?]
	at net.minecraft.network.protocol.game.ServerboundChatPacket.handle(ServerboundChatPacket.java:6) ~[?:?]
	at net.minecraft.network.protocol.PacketUtils.lambda$ensureRunningOnSameThread$1(PacketUtils.java:56) ~[?:?]
	at net.minecraft.server.TickTask.run(TickTask.java:18) ~[patched_1.17.jar:git-Purpur-1231]
	at net.minecraft.util.thread.BlockableEventLoop.doRunTask(BlockableEventLoop.java:149) ~[?:?]
	at net.minecraft.util.thread.ReentrantBlockableEventLoop.doRunTask(ReentrantBlockableEventLoop.java:23) ~[?:?]
	at net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:1413) ~[patched_1.17.jar:git-Purpur-1231]
	at net.minecraft.server.MinecraftServer.shouldRun(MinecraftServer.java:193) ~[patched_1.17.jar:git-Purpur-1231]
	at net.minecraft.util.thread.BlockableEventLoop.pollTask(BlockableEventLoop.java:122) ~[?:?]
	at net.minecraft.server.MinecraftServer.pollTaskInternal(MinecraftServer.java:1391) ~[patched_1.17.jar:git-Purpur-1231]
	at net.minecraft.server.MinecraftServer.pollTask(MinecraftServer.java:1384) ~[patched_1.17.jar:git-Purpur-1231]
	at net.minecraft.util.thread.BlockableEventLoop.managedBlock(BlockableEventLoop.java:132) ~[?:?]
	at net.minecraft.server.MinecraftServer.waitUntilNextTick(MinecraftServer.java:1360) ~[patched_1.17.jar:git-Purpur-1231]
	at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1271) ~[patched_1.17.jar:git-Purpur-1231]
	at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:322) ~[patched_1.17.jar:git-Purpur-1231]
	at java.lang.Thread.run(Thread.java:831) [?:?]
Caused by: java.lang.NoSuchMethodError: 'net.minecraft.nbt.NBTBase net.minecraft.nbt.NBTTagList.k(int)'
	at io.lumine.xikage.mythicmobs.volatilecode.v1_17_R1.CompoundTag_v1_17_R1.fromNMSTag(CompoundTag_v1_17_R1.java:184) ~[?:?]
	at io.lumine.xikage.mythicmobs.volatilecode.v1_17_R1.CompoundTag_v1_17_R1.fromNMSTag(CompoundTag_v1_17_R1.java:167) ~[?:?]
	at io.lumine.xikage.mythicmobs.volatilecode.v1_17_R1.VolatileItemHandler_v1_17_R1.getNBTData(VolatileItemHandler_v1_17_R1.java:58) ~[?:?]
	at io.lumine.xikage.mythicmobs.items.MythicItem.addItemNBT(MythicItem.java:631) ~[?:?]
	at io.lumine.xikage.mythicmobs.items.MythicItem.generateItemStack(MythicItem.java:512) ~[?:?]
	at io.lumine.xikage.mythicmobs.commands.items.GetCommand.onCommand(GetCommand.java:74) ~[?:?]
	at io.lumine.xikage.mythicmobs.utils.commands.Command.onCommand(Command.java:64) ~[?:?]
	at io.lumine.xikage.mythicmobs.utils.commands.Command.onCommand(Command.java:55) ~[?:?]
	at io.lumine.xikage.mythicmobs.utils.commands.Command.onCommand(Command.java:61) ~[?:?]
	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:45) ~[patched_1.17.jar:git-Purpur-1231]
	... 21 more