I've got two tables and two pivot tables for each of them respectively. In the first table, the duration of each task is calculated on a column called "duration", but in the second one, there is no such column and duration of each task is a calculated field in the pivot table. As you can see, in the first pivot table, tasks with zero time are not shown. But in the second pivot table, where durations are calculated fields, zero time tasks are shown as "0:00". How can I hide zero times like in the first table?