Copilot Notebook Sees 78 Files but Only Accesses About 20. Why?

The notebook’s file count and Copilot’s answer about what it can see are different signals. Microsoft documents up to 300 grounding references for licensed Microsoft 365 Copilot Notebooks, while Copilot Chat notebooks have a 50-reference limit. Neither documents a general twenty-file limit.
First confirm the account’s exact notebook entitlement. Your Word, Excel, and PDF formats are supported, but a folder appearing in the interface does not establish that every file’s contents were used in a response. Copilot’s self-reported inventory is not a definitive diagnostic.
For a support case, select one allegedly inaccessible file that you can open directly, identify a distinctive passage, and record whether a targeted question retrieves that passage with a citation. Provide the notebook identifier, file count, permissions, client version, timestamps, and reproducible example privately.
This post cannot establish a Microsoft-confirmed cause. A service-side investigation is needed before blaming an undocumented regional or file-count restriction.

Hi,

I checked Microsoft's documentation on Copilot Notebooks. Here are a few things worth investigating.

1. Check the reference limits

Microsoft documents different reference limits depending on your license:

• Microsoft 365 Copilot users can add more than 300 references, but only the first 300 are used for grounding.
• Copilot Chat users can add up to 50 references.

Since your notebook contains 78 files, this does not appear to be a documented 20-file limit.

Official documentation:
https://support.microsoft.com/en-us/microsoft-365-copilot/add-references-to-your-microsoft-365-copilot-notebook

1. Check whether Copilot can read individual files

Seeing 78 files listed does not necessarily mean Copilot retrieves content from every file for every question. It selects relevant information based on your prompt.

Try asking Copilot to summarize a specific document by its exact filename. Test this with a Word document, a PDF, and an Excel workbook.

If individual files work but broader questions only use some sources, the issue may be related to content retrieval or relevance.

1. Check file formats, permissions, and folder references

Confirm that the files use supported formats and that you can open them directly. Also, try adding one problematic file individually instead of relying only on the folder reference.

Microsoft's documentation explains how Copilot Notebooks uses references:
https://support.microsoft.com/en-us/microsoft-365-copilot/how-microsoft-365-copilot-notebooks-works

My conclusion:

I couldn't find official Microsoft documentation confirming a 20-file retrieval limit for Copilot Notebooks. If the issue persists, report it through the Microsoft 365 Copilot feedback mechanism and include your license type, file formats, and a reproducible example.

One question that could help narrow this down: Are you using Microsoft 365 Copilot Notebooks with a work or school account, or Copilot Chat?

If this helps, please like the response.

Connect with me on LinkedIn:
https://www.linkedin.com/in/sapan-patel-807321222/