Temporal Statistics Filter do not compute over entire domain

I have a dataset with 19 time steps, I want to compute temporal average over the domain. I use the temporal statistics filter, but the filter computes the average partially over the domain. I have attached the two phots. One is instantaneous velocity contour, other is the averaged velocity contour on a plane.

How do I make paraview compute average across the entire domain? The drop down list of variables also shows “u_mean (partial)”.