Cinemachine logo doesn't appear in the hierarchy beside the Main Camera object. Only happens in a fresh project. For some reasons, the logo needs to be loaded somehow. The logo will only appear once we enter in Play mode. Then the logo will appear for good.

1. Start a fresh project in Unity 2019.1
2. Install Cinemachine preview package 2.3.0-preview.2
3. In the current scene, create a Virtual Camera from the Cinemachine menu
4. This process should create a Brain on the main camera and usually, the cinemachine logo should be display beside the Main Camera object from the hierarchy

Result
The Logo doesn't display

5. Save the scene and open a new scene
6. Repeat Step 3 ... still no logo
7. Load back the first scene, the logo won't be there either
8. Now press Play ... the logo will then display in the hierarchy as it should
9. At that point, the logo will always appear from now on when a Brain is added to a camera.