Milestones in project management can be missed for a variety of reasons, including:

1. **Poor Planning**: Inadequate initial planning, unrealistic timelines, or insufficient resource allocation can lead to missed milestones.

2. **Scope Creep**: Changes in project scope without proper adjustment to timelines or resources can derail progress.

3. **Lack of Communication**: Ineffective communication among team members and stakeholders can result in misunderstandings and delays.

4. **Resource Availability**: Unforeseen circumstances such as team members leaving or resource shortages can impede progress toward milestones.

5. **Risk Management**: Failure to identify and mitigate risks can lead to issues that cause delays in meeting milestones.

6. **Dependency Delays**: If a task is dependent on another, delays in the preceding task can push back subsequent milestones.

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