Ship To disappears

R11.5.10

Just applied RUP12

I have an intermittent error occuring when viewing or modifying a PO created through the release process.  Always, after the PO is queried, I can see the ship to location on the first 4 rows created.  BUT when I page down to see the next group of rows,SOMETIMES  the ship to address is missing and the form demands it be input.  I checked the PO line loctions all, and the ship_to location is indeed stored so it should display on the lines.  It is the same locations as stored on lines 1 - 4 so it definately is a good location.