How to reproduce it:
1. Open an attached project '1282859.zip'
2. Load 'Scene' scene from 'Assets' folder
3. Select 'Capsule' GameObject
4. In the Toolbar click on 'Screen Scale Tool'
5. On the bottom-right corner 'Helper' window appears and click on the 'Snap to floor' button
6. Notice that the 'Capsule' snaps to the floor
7. Move the 'Capsule' GameObject back up
8. In the Scene view control bar enable the 'Component Editor Tools panel' switch
9. Click on 'Snap to floor' button

Expected result: 'Capsule' GameObject snaps to floor
Actual result: 'Capsule' GameObject is deselected and does not snap to floor

Reproducible with: 2019.4.11f1, 2020.1.8f1, 2020.2.0b6
Could not test with: 2018.4 (Editor tools feature not introduced)