Emission property in material can’t be changed when using script if the initial value in the material is black

How to reproduce:
1. Open the user’s attached “setEmission.zip” project
2. Enter Play Mode
3. Press the “Spacebar” button
4. Observe the result

Expected result: Plane’s color has changed
Actual result: Plane’s color doesn’t change

Reproducible with: 2021.3.34f1, 2022.3.19f1, 2023.2.8f1, 2023.3.0b6

Reproduced on: macOS 14.2.1 (Intel)
Not reproducible on: No other environment tested

Note: not reproducible if materials emission color is not black