Error + delayed playing of songs with WorldGuard integration

Hi, I have an issue with WorldGuard integration. I've enabled "region folders", and when I place music inside them and reload plugin it works, but with noticable delay of like 10s when switching between regions, and when I checked my console, it spams me with this error:

[12:27:26] [Server thread/WARN]: [AdvancedNBS] Task #294 for AdvancedNBS v0.4.2 generated an exception java.lang.NoSuchMethodError: org.bukkit.scheduler.BukkitTask.isCancelled()Z at com.iiztp.anbs.utils.Utils$1.run(Utils.java:44) ~[?:?] at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftTask.run(CraftTask.java:59) ~[patched.jar:git-PaperSpigot-"4c7641d"] at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:352) [patched.jar:git-PaperSpigot-"4c7641d"] at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:783) [patched.jar:git-PaperSpigot-"4c7641d"] at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:378) [patched.jar:git-PaperSpigot-"4c7641d"] at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:713) [patched.jar:git-PaperSpigot-"4c7641d"] at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:616) [patched.jar:git-PaperSpigot-"4c7641d"] at java.lang.Thread.run(Unknown Source) [?:1.8.0_271]

(It repeats, constantly spamming console) I'm using PaperSpigot for 1.8.8 from their website (latest version). I also have NoteblockAPI installed.