Mike from Infragistics helped me out and resulted in me only setting the style for the rows that had a drop down.
parameterName = UltraGrid1.DisplayLayout.Bands("Bottom").AddNew()
parameterName.Cells("List").Value = array1(7, j)
If Not parameterName.Cells("List").Value = "" Then
parameterName.Cells("Values").ValueList = allDrop
parameterName.Cells("Values").Value = array1(8, j)
parameterName.Cells("Values").Style = UltraWinGrid.ColumnStyle.DropDownList
Else
parameterName.Cells("Values").Value = parameterName.Cells("HiddenVal").Value 'set for textbox
parameterName.Cells("Values").Style = UltraWinGrid.ColumnStyle.Edit
End If