Copilot, limitations?

Thank you for the follow-up — and I genuinely understand your frustration. You’re not wrong that, from a human perspective, this is a very simple arithmetic problem, and yes, ChatGPT can solve it easily.

However, the key point is that Copilot in Power BI is not failing at math — it is refusing to cross semantic boundaries it is not allowed to cross.

What you are describing is a cross-report reconciliation problem, not a calculation problem.

When you say:

“Report A says 100,000 passengers in November
Report B splits November into 80,000 NS and 20,000 SN
How many of the 100,000 are NS vs SN?”

For a human (or ChatGPT), the assumption is obvious: they refer to the same population.

For Copilot:

These are two separate semantic models

There is no guaranteed relationship

There is no shared grain or lineage

There is no enforced business rule that NS + SN = total passengers

Copilot is designed to not assume equivalence, even when it seems obvious.

That’s why it asks for:

The exact measure

The exact table

The exact relationship

All data inside the same model

It’s not intelligence vs stupidity — it’s governance vs inference.

Why ChatGPT “works” here

ChatGPT:

Assumes the numbers are compatible

Ignores data lineage

Doesn’t care if the logic would be invalid in a governed BI system

Copilot:

Must avoid generating potentially wrong business answers

Cannot reconcile two reports unless they are backed by the same dataset

Cannot “peek” into another report or model

The real limitation (and you’re right to call it out)

Where I agree with you 100%:
Copilot does not currently help enough with reconciliation-style reasoning, even when:

Measures exist

Names match

Logic is obvious to a human

That does limit its usefulness today for analysts doing validation, reconciliation, or sanity checks across reports.

So yes — for this use case, Copilot is not helpful. That’s a fair and valid conclusion.

The practical takeaway

Copilot works best when:

All numbers live in one semantic model

Relationships are explicit

Measures are already defined

For:

Cross-report summaries

Reconciliation

“Explain the difference between report A and report B”

Today, external reasoning tools (like ChatGPT) are still better.

You’re not misunderstanding Copilot — you’re simply hitting a real product boundary. Calling that out is fair, and it’s exactly the kind of feedback Microsoft needs to hear.

If this explanation helped clarify why this happens (even if you still disagree with the design), please consider giving Kudos 👍 and marking as the Accepted Answer ✔ so others don’t hit the same frustration without context.