All TimeTracker users do not see all the Projects in your org, due to sharing rule settings.
If the objects, Project and Project Assignment are set to Private, only the Admin sees all the Projects in your org. As the users do not have access to the Projects, they don't see all Projects for tracking time.
Change the objects setting to Public Read/Write by following the instructions below
- From the Salesforce Admin ID, click the Setup button,
- Search for Sharing Settings in the Quick Search,
- Click Edit in the Sharing Settings screen,
- Scroll down to Project and Project Assignment and change the default internal access to "Public Read/Write,
- Save it,
- Now the user will have access to all Projects in your org.
Or, you can also create a separate rule via the public group. Click here to know more.