It may be that the uploaded table is not counting the table join fields as fields,
which ArcMap does not either.
One approach is to create new fields next to those join fields, name them accordingly,
set the data type to text (works for all numbers as well), then go into field calculator and
set them equal to the join fields.(or something like that)
You can then edit out the joined fields by removing the join and you should have a complete
upload ready shapefile with your custom attribute fields.