I have:

-Created a timetable: monday to friday 10h to 18h [using Configuration > Resources > Working Time], created resource [name: Admin, user: Administrator] and asigned the created timetable.

-Created a Project Pr1 and assigned my resource (Admin).

-Created two Phases FA (duration 10 hours) and FB (duration 15 hours) and assigned the only resource of the project to these phases.

-Used the Phase Planner to program my project.

The Gantt obtained is inconsistent with the defined project and phases: the duration of FA shown in the diagram is 8.666666 hours and 15.66666 for FB