A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data
I figured out the cause.
In Options, under "Data" and "Automatic data conversion", the default for "Remove leading zeros and convert to a number" was enabled. Unchecking that option worked.
Which begs the question, why is data to columns affected by a setting that sounds like it should only affect numbers coming from outside of excel?
In any case, I solved my own issue.