How to reproduce:
1. Open the "SampleScene" Scene in the attached "case_1153034.zip" Unity project
2. In the Hierarchy tab, select the "Plane" GameObject
3. Open the "Edit cloth self/inter-collision" window in the Inspector
4. Select any vertices in the Scene tab and untick "Self-Collision and Inter-Collision"
5. Re-select the "Plane" GameObject and open the "Edit cloth self/inter-collision" window
-- Observe the Scene view

Expected result: the previously selected vertices do not have Self-Collision and Inter-Collision
Actual result: some previously selected vertices retain Self-Collision and Inter-Collision

Reproducible with: 2017.4.27f1, 2018.4.0f1, 2019.1.3f1, 2019.2.0b2, 2019.3.0a2

Note: in Unity versions 2019.1.3f1 and later, applying Self-Collision and Inter-Collision onto a few vertices is not possible. If Self-Collision and Inter-Collision are applied onto the entire GameObject, an attempt to remove Self-Collision and Inter-Collision from a few select vertices will remove Self-Collision and Inter-Collision from all vertices instead. After pressing "Play", parts of the "Plane" GameObject disappear and some mesh faces turn black.