When adjusting a boolean value through the Task Timeline (Modern User Experience (UX) "Gantt") view on the left-panel side, it does not save / retain. The option can be checked in the Timeline, but it's not actually saving the change.
This impacts all checkbox values on the Timeline view, which includes:
Expected Results: The Task should now be included in the Status Report.
Actual Results: Checking the box from the Timeline does not save the attribute update.
Release : 15.9.3
Component : Clarity MUX UI Usability
Fixed in 16.0 for all boolean fields
Note: As part of the updates in 16.0, you will also now correctly see a warning message if you try to make a parent task (Summary task) a milestone, informing you that it's not allowed.
You can update the value if you add the field to the column list.