Okay, I just tried this and changed all the items to noninventory. I went to do the upload and it converted the columns to Inventory!! I made sure there was no asset account (no data in the column)

I called support and got someone who told me I can't export inventory items. I told her to have a nice day. LOL

Let me know if you have any other thoughts.  My client has almost 1,000 items.