The User Column in Summary Table doesn't display the same result as the same User Column in the Result Table.

If you add a User Column to both the Summary and Result Table containing the same formula, often you cannot get the same results. You cannot use the First, Last, etc. functions from Special Values in the Summary Table. For example, "[Reten. Time]first/[Reten. Time]" will not work here. But you can use figures working with the compound itself, for example "[End Time]-[Start Time]".