Reproduction steps:
1. Open user attached project "UnityBugTest2"
2. In the Project window, select "sprite2"
3. In the Inspector, change Platform Specific overrides Max Size value to 8192 and hit "Apply"
4. Right-click on the Header and press "Reset"

Expected result: Changed value is reset and is updated in the Inspector
Actual result: Changed value is reset but the Inspector is not updated

Reproducible with: 2019.2.0a1, 2019.2.11f1, 2019.3.0b9, 2020.1.0a11
Not reproducible with: 2017.4.34f1, 2018.4.12f1, 2019.1.14f1

Note: If a Preset is applied to the Import Settings, Platform Specific overrides also are not updated in the Inspector