Strategies for handling Source Attribution Decay / Context-History Contamination?

My RAG works pretty well. It sticks to the context and retrieves with high precision because that is what we fine-tuned it for during benchmarking. However, now that we're testing we've noticed a big problem: with a few turns of a conversation, it starts hallucinating false citations.

It seems that if a user asks something that it cannot answer, it reasserts facts from its message history and then randomly cites one of the documents from its current context.

Is this a known limitation with RAG? or are there proven strategies to counter this?

A bit more context: we have tried appending guardrails to each message to fix this, but no luck so far. These are the relevant points from the guardrails:

2. **NO INVENTIONS**: Only state what the provided sources say. If the information is missing, admit it, explain what was found instead, and ask for clarification or offer a new search path. NEVER return an empty response.
3. **CITATIONS**: Use [N] markers naturally in prose. Do not list sources at the end.
4. **CITATION DRIFT**: Do not use the current context's source numbers to cite facts remembered from previous turns. If a source is no longer in the current context, do not cite it.2. **NO INVENTIONS**: Only state what the provided sources say. If the information is missing, admit it, explain what was found instead, and ask for clarification or offer a new search path. NEVER return an empty response.
3. **CITATIONS**: Use [N] markers naturally in prose. Do not list sources at the end.
4. **CITATION DRIFT**: Do not use the current context's source numbers to cite facts remembered from previous turns. If a source is no longer in the current context, do not cite it.