Added ReadyForEntityUpdates message allowing the server to send entity updates

Gems/Multiplayer/Code/Source/NetworkEntity/NetworkEntityManager.cpp

@@ -11,19 +11,19 @@
  */
 
 #include <Source/NetworkEntity/NetworkEntityManager.h>
-#include <Source/Components/NetBindComponent.h>
-#include <Include/IMultiplayer.h>
-#include <AzCore/Interface/Interface.h>
+
+#include <AzCore/Asset/AssetManager.h>
 #include <AzCore/Console/IConsole.h>
 #include <AzCore/Console/ILogger.h>
+#include <AzCore/Interface/Interface.h>
 #include <AzCore/Serialization/SerializeContext.h>
 #include <AzCore/Slice/SliceMetadataInfoComponent.h>
+#include <AzFramework/Components/TransformComponent.h>
 #include <AzFramework/Entity/EntityContextBus.h>
 #include <AzFramework/Entity/GameEntityContextBus.h>
-#include <AzFramework/Components/TransformComponent.h>
 #include <Include/IMultiplayer.h>
 #include <Pipeline/NetworkSpawnableHolderComponent.h>
-#include <AzCore/Asset/AssetManager.h>
+#include <Source/Components/NetBindComponent.h>
 
 namespace Multiplayer
 {
@@ -462,7 +462,9 @@ namespace Multiplayer
 
         m_rootSpawnableAsset = netSpawnableAsset;
 
-        const auto agentType = AZ::Interface<IMultiplayer>::Get()->GetAgentType();
+        auto* iMultiplayer = AZ::Interface<IMultiplayer>::Get();
+
+        const auto agentType = iMultiplayer->GetAgentType();
         const bool spawnImmediately =
             (agentType == MultiplayerAgentType::ClientServer || agentType == MultiplayerAgentType::DedicatedServer);
 
@@ -470,6 +472,12 @@ namespace Multiplayer
         {
             CreateEntitiesImmediate(*netSpawnable, NetEntityRole::Authority);
         }
+        else
+        {
+            // If we don't spawn net entities immediately (i.e. it is a client),
+            // tell the server/host it can start sending updates that will instantiate entities.
+            iMultiplayer->SendReadyForEntityUpdates(true);
+        }
     }
 
     void NetworkEntityManager::OnRootSpawnableReleased([[maybe_unused]] uint32_t generation)