I found the issue and corrected it. The irony is that the file was failing one of my own security checks. For some reason the file type was being determined by PHP to be text/html. Since I only permit CSV files the check would fail. I think it is detected as HTML due to the HTML within the file itself. PHP seems to have guessed and guessed incorrectly. The only fix was to allow text/html files. I made the tweak so it should work fine now.
Let me know.