view gannt problem

I cannot make “view gannt” function of project work correctly.
please see the snapshot.

The first task only has one day duration, but in the gannt chart, the span of days is the number of days of whole project.
And, the task 3 does not show in the chart.

I have no idea how to make it work.

The version of suitecrm I am using is already 7.7.9.


I have the same problem in version 7.7.9 the diagram does not show the actual duration of the tasks.

In version 7.7.8 this version displayed correctly.

How can we solve this problem?

Thank you