There are a few ways to fix it:
(*) Resize – move your mouse cursor all the way to the left (to where the row numbers should be) at the column header level, when the cursor changes to the black resizing arrows, grab it and move to the right. This will change only one column size.
(*) Reset – click with right mouse button anywhere on the List/grid and pick “Reset Default Properties” from the menu. This will reset all the columns on the given List.
(*) Start Over – with your job still opened, go to the Windows Explorer and navigate to the job directory; locate and delete the file .GRD (all the Lists properties are stored there). Then close the Piping Input processor and reopen it again. This will reset formatting on all the Lists.