How to reproduce:
1. Open the attached “IN-151689_UIToolkit_DropdownField_InitialValueRepro” project
2. Open the “TestScene" scene
3. Enter Play Mode
4. Observe the diagnostics label in the Game view
Actual result: Both tests fail with both test indexes returning -1
Expected result: Both tests succeed with correct indexes being returned
Reproducible with: 6000.6.0a5, 6000.6.0b10, 6000.7.0a5
Not reproducible with: 6000.0.82f1, 6000.3.23f1, 6000.5.10f1, 6000.6.0a4
Reproducible on: Windows 11, macOS 26.5.2 (User reported), macOS Sequoia 15.7.7 (M1 Max)
Not reproducible on: No other environment tested