Reproduction steps:
1. Open the attached "case_1307577.zip" project
2. In the Project window, select Localization Settings asset
3. In the Inspector, expand Specific Locale Selector and change Locale Id to English (by using Object Picker)

Expected result: Locale Id field is updated
Actual result: Locale Id field is not updated

Reproducible with: 0.10.0-preview (2019.4.19f1, 2020.2.3f1, 2021.1.0b5, 2021.2.0a3)
Not reproducible with: 0.8.0-preview - 0.9.0-preview (2019.4.19f1, 2020.2.3f1, 2021.1.0b5, 2021.2.0a3)
Could not test with: 2018.4.31f1 (could not downgrade)

Notes:
1. Locale Id field is updated after reopening the Inspector window
2. Locale Id field is updated when dragging and dropping the Locale asset
3. Specific Locale Selector/Code is properly updated