When adding or moving around songs in the sets of any show using the Edit Songs tab, I see the number of songs of each set as well as the total duration time of the set displayed at the top of each set, EXCEPT for the first set, which only shows the number of songs. This is also true in the layout view of the show. Only the number of songs in the first set is shown without the duration of the set.
This is most likely because one of the songs in that set doesn't have a duration defined, so the total can't be calculated. You can either define a duration for every song, or set a default song duration on the show's Edit Details page (and set a default song duration on the Settings > General Settings page for all future shows).
Thanks