xlsxwriter module is apparently found by py2app, but doesn't work in compiled app

[RandallWert]

I have written a Python 3.9 app that imports xlsxwriter to create an Excel file. When I run the program from my IDE, it works fine, and the Excel file is created successfully. Then I compile it by the usual py2app method. I don't get any error messages about xlsxwriter not being found, so the compilation seems to run successfully. But when I run the compiled app, it does not create the Excel file.

Some places like stackoverflow tell people to use a specific filepath (not just the filename) when opening the Workbook object. I have changed my code to do that, but the problem remains exactly as described above.