This occurs in 12.0 and 13.0 on all platforms 

1. select top 15 * from SQL Server 2000 Northwind Orders table and press enter a few times to make some blank lines in the Query Analyzer, then Execute

2. in the Grid Results drag a selection of cells beginning in row 3 with EmployeeID and ending in row 11 with RequiredDate

3. with all of those cells selected, right click on top of this selection and Copy

4. with those cells still selected, right click again and choose "Paste to Window" > "UPDATE Body"

5. take a look at the resulting Update statement that gets pasted in the Query Analyzer.
Notice that the first column it wants to update is OrderID, even though we didn't select that in the Grid.

6.  It looks like the UPDATE is pulling the data from the cells we selected, but it is using the incorrect column names (it wants to use the very first columns of the Results, not the column headers of our selection from the Grid)

see attached