I'm having the same problem, too. Any updates on what it could be? On the surface, I have named all the fields in the Excel file accordingly, and the categories and manufacturers are loading correctly. But nothing else besides that.
I also need to change the location of the temp file, since my store doesn't sit on any subfolders (it's right on the root). I see
"$tmpfname = DIR_FS_DOCUMENT_ROOT . EP_TEMP_DIR .
But I also have no idea what to change it to. Any suggestions, please?