Starting with, I believe the 12/15 update, if you don't print a Packing List with the Ship date, you have to put in either a Ship Date or Invoice Date in SO-F or it will print with 00/00/00. We have our defaults set the same as yours. However, in order for it to work, you have to <Enter> down to the "Override with this Ship Date" for it to fill in today's date.
 
Again, this is only if you didn't print a Packing List with a ship date. And we don't on CODs and CC orders since we send an Invoice, not a Packing List with those.