Partial update feed inventory file

Morning everybody

I am trying to add new listings to my inventory and having some trouble. 2 separate items, listed in the beauty category. I have included all relevant information, EAN, title, descriptions, images etc, yet when I save and finish they keep going into ‘Drafts’.

When I am in drafts, there is a message that information is missing. First, this was item title, yet when I clicked ‘edit’, this was already filled in (as I thought it was). Speaking with SS, they have informed me that there is an issue with the SKU of the items and now the error message says my SKU is missing (no longer the item title).

SS have said I need to do a partial file upload due to a SKU error. So my questions are;

1. How do I do a partial file upload? I have tried to search and find any links in ‘help’ but just come back with partial refunds. I usually list all my items individually, not via a file.
2. Is this an error I have somehow created, seeing as I have already included and updated the SKU when requested to, or is this something that the Amazon system now requires?

Thank you kindly for your time