[=The Beej;98570]
UActorChannel needs to be #included when doing actor subobject replication
#include "Runtime/Engine/Classes/Engine/ActorChannel.h"
If you’re doing replication of custom subobjects in your actor, then you will now have to include UActorChannel’s header for Channel->ReplicateSubobject() to compile. Also, RF_WasLoaded flag is no longer needed for your replicated subobject to be supported for networking, instead override bool UObject::IsSupportedForNetworking() to return true.
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Wow really useful info, Thanks The Beej!