What seems to happen is that an empty grid is created with the proper td attributes, but the empty grid does have enough blank rows to match the new larger page size.
For example, start with a page size of 3, a blank 4 row grid is created then populated with data, with the last row being removed. I think the extra row is for the optional footer, which the grid does not have. Change the page size to 10. After the postback, a blank 4 row grid is created, then populated with 10 rows, which properly expands the visible rows to 10, but the last six rows lack formatting attributes.
I’m not sure the best way to handle this issue.