Limitations of Microsoft 365 Copilot for Excel workflows?

Yeah the messy data thing is probably the biggest gap right now. Copilot works best when data is already in a clean table format with proper headers. For the PDF/image to table stuff, I've had better luck using Copilot in Edge to extract the data first, then pasting it into Excel and cleaning up from there.

What I do is use Copilot for the quick stuff like "sum this column" or "create a chart from this data" and keep Power Query for the heavy lifting. 

For these types of more complex scenarios, I find Claude for Excel (Excel Add-in) from Anthropic is a much better option that Copilot. Claude for Excel can handle extremely complex and messy datasets across multiple files. Of course, it would be an additional cost but worth having a look at if this is something you are specifically looking at.

Edit in Copilot (AKA. Agent Mode) for Excel using the Claude models (Claude Opus 4.5 or 4.6) will give you a much better result than relying on the GPT-5.x models. Note that you would need to enable Anthropic sub-processor in order to get the Claude models available in Excel.

Microsoft 365 Copilot in Excel is helpful for analyzing data and generating formulas, but it does have some limitations. For example, it may struggle with very complex workflows, large datasets, or highly customized formulas. It also depends heavily on how clearly you describe what you want, and sometimes the results still need manual verification. So while it can speed up tasks, it’s not a complete replacement for advanced Excel knowledge yet.

Hi

I don't rely on any AI tool by 100% , But i found it great by 90% .

For all these jobs in am Using new Copilot Cowork instead of Copilot in Excel .

you may refer Cowork Samples here Copilot Cowork