Tracks are not shown in the "Add Tracks" dropdown when their name begins with a '/'

How to reproduce:

1. Open the attached project “IN-145378”
2. Open the “Assets/Scenes/Timeline” Timeline
3. In the Timeline window, press the '+' button in the top left corner
4. Observe the dropdown list

Actual result: “Example.Custom4” is not shown in the list
Expected result: “Example.Custom4” is shown in the list

Reproducible with: 1.8.6 (6000.0.0f1), 1.8.12 (6000.5.0f1), 6.6.0 (6000.6.0a7)

Reproducible on: macOS 26.5 (M4 Max), Windows 11
Not reproducible on: No other environments tested

Note: The “Custom4Track” script contains the following DisplayName: “[DisplayName("/Custom4 Track")]”