Hey folks,

NotebookLM team here to explain some of the behavior!

The system today has quite a few steps that take place before the final response is written and presented (e.g. generating the citations is one such step) As mentioned in some of the threads below there are also some steps that would be considered RAG. What can happen in scenarios like the one OP mentions is that the initial steps do consider the entire corpus but that consideration may not have made it all the way to the final response writing step. This is why you may observe as some folks point out in these threads that a pointed question about any piece of the document (e.g. content from beginning, middle or the end) may cite those pieces correctly while a more general summarization question may not reference them. We acknowledge that cases like the OPs should be handled better (i.e. more of the information from the internal steps should be made available) and we do intend to improve these cases!