Why is the project drop-down menu in the Track view empty?

This usually means that you are not yet assigned to any projects. To track time on a project, you need to follow these steps:

1. Create a Project
2. Assign yourself or your team members to it (PRO)
3. Select your Project on the Track page 

If you are not an owner or administrator of your account, make sure that your administrator has assigned you to projects.