Outlook for Mac File Save Dialog Picks Wrong Email Attachment?

I routinely receive emails with 6+ files attached. These files have various file types - html, pdf, csv, etc. The filenames are broadly similar - think ${Company_name}-${Tool_that_prepared_report_name}-${thing_tool_was_run_on}-${random_id}. This usually looks like the following:

My_Company_Tool_A_Product_1_1234.html

My_Company_Tool_A_Product_1_1234.pdf

My_Company_Tool_A_Product_1_1234.csv

etc.

When I try to save the *.html version of this file out to the filesystem on my Mac, Outlook instead (inconsistently) picks the *.pdf file that is attached to the same email. I can't tell if there is a sequence of actions on my part that I'm doing to have outlook pick the wrong version of the file, but when I select the "cancel" button on the "File Save" dialog and then attempt to download THE SAME FILE from Outlook, it picks the correct (*.html) file. I have checked my workflow several times, and I believe that I'm selecting the *.html file every time.

How can I prove that my workflow is correct? I know this sounds extremely dubious, but I think I'm doing everything right. I don't want to do a screen recording because this potentially has security implications, but I don't know how to prove that my workflow is correct. I think there's a bug in outlook, but I don't trust that what I'm doing is what I think I'm doing.