When your timeline contains milestones that are on the same date as a task’s End Date, the milestone marker does not align to the task bar as you would expect.
By default, Office Timeline places the end of a task bar at the end of the working hours, while milestones, unless set otherwise by the user, are placed at the beginning of the day. In the case of long-term projects that span over a year, this slight difference isn’t visible on the graphic. However, on short-duration timelines, you may need to set the milestones’ placement at the same time of the day as the tasks to have them aligned as expected. This can be easily done from the Edit Data wizard.
From your timeline, click on the Edit Data button on the Office Timeline ribbon to open the wizard.
Here, click on Add column (+) and switch on Hours and Minutes. This will show the Start Time and End Time columns in your table.
Now, change your milestones’ End Time so as to be identical to the tasks’ End Time.
Click Save, and you will notice that your milestones and tasks are now aligned properly.