In our previous version 14.2, the column in a portlet has a top alignment, but in version 15.5.1 the column has a middle alignment. Why?
Release: Component: PPMSTU
In old CA PPM versions, the data used to show aligned to top for some portlets and that was reported as a defect and fixed in the latest releases. That is why you are seeing the alignment correctly in CA PPM 15.5.1. Hence, this is not an issue but working as per the design.
In the grid portlet, for the display attributes we have an option for alignment. This could be left, right or center. This alignment is only about horizontal alignment. There is no option to configure or modify the vertical alignment for the cells of a grid portlet.