Copilot Agent AND notebook have trouble examining excel xlsx file

https://1drv.ms/x/c/047c12ac071676ec/IQA0n01R4RpJRoCCqTtdlrp5ASE85N8T8yXax1WKCQrePH4?e=gfzcT9

Uploading this same file to a custom agent AND setting up a new notebook with this one excel files gives errors - inability to access contents. 

I've tried multiple iterations of similar excel files (.xls, .csv, xlsx) - 300 rows by 5 columns with dummy data in each and simply asked sum the column called Base Market Value.  

If i put the file in a general chat, it does calculation without issue.

Appreciate any help as this is extremely frustrating.
Wolly

PS below is the basic response i get.  Despite my confirming that it has the right column name, it can't calculate it.   Or in one case, it calculated the figure incorrectly