Testing:

You will need to use data (see linked support issues) that has null fund/function/asset classes on items.  Export the item from the grid and set a valid fund/function/asset class on the item.  Use the importer to update the item.  You will need to make sure you have Create Transfers selected, along with a transfer date in the current fiscal year.  The Update Records option must also be selected.  Verify that the item has updated after the importer has finished.  Note:  if you're using the regular importer (System->Import), the item's acquisition date needs to be in the current fiscal year.  If you use the Migration Importer (System-> Configuration->Migration Importer), it should work for any item, regardless the acquisition date.