In Director -> Trends -> Create Custom report in the case of an English locale  the dates appear in 12 hour format wiith AM\PM shown.

This is seen even in the report preview before exporting the data . AM\PM denotes 12 hour format.

This is by design.

With Director 2402 the date format will match the language locale of the user machine running Director.

This is a change from Director 2203 .

In the case of En_GB or EN_US the format will be 12 hour format .

In the case of other locale such as French the format will be 24 hour format . The locale can be identified in the Director URL. In this  example fr means that the date will be shown in 24 hour format.

Problem Cause

This is by design.