It is definitely the font choice. My file used Avenir and once I changed it to anything else and saved it, no problem.
taragardner
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Big Sur update, some text files open as blank files in Text Edit. From both Recents and Open. If I access the file directly from Finder I can see the text and it opens ok in Text Edit. I had moved the Relocated Items folder to Trash. Moved it back to desktop, same thing.