Generative AI Hallucinations: Is there ANY robust solution beyond RAG?

I've been battling persistent hallucinations with our internal LLM, even with a robust RAG setup. It's frustrating when accurate data is available but the model still fabricates. Are there any truly effective, proven strategies or emerging techniques beyond just improving RAG that people have found success with for minimizing or eliminating these issues in production? I'm really keen to hear practical insights.