How to reproduce:
1. Open the attached project named "line bug"
2. Open the Scene named "bug" and select the Line object in Hierarchy
3. Click on the "Edit Points" button for the Line Renderer
4. Select one of the Line points from the "Positions" list in the Inspector window

Expected result: Scene view updates the Gizmo to highlight the selected point immediately
Actual result: Scene view does not update the selected point until the mouse cursor is moved to the Scene view or the point properties are changed

Reproducible with: 2019.3.0f1, 2019.4.11f1, 2020.1.6f1, 2020.2.0b3
Not reproducible with: 2018.4.27f1, 2019.3.0b12

Notes:
1. "Simplify Preview" was also affected by this, but it was fixed in 2020.2.0b2