paper-server/src/main/java/org/bukkit/craftbukkit/CraftServer.java

@@ -2550,7 +2550,7 @@ public final class CraftServer implements Server {
 
     @Override
     public boolean isPrimaryThread() {
-        return Thread.currentThread().equals(this.console.serverThread) || this.console.hasStopped() || !org.spigotmc.AsyncCatcher.enabled; // All bets are off if we have shut down (e.g. due to watchdog)
+        return ca.spottedleaf.moonrise.common.util.TickThread.isTickThread(); // Paper - rewrite chunk system
     }
 
     // Paper start - Adventure