How to reproduce:
1. Open User's attached "bug-MouseDelta.zip" project
2. Enter the Play mode
3. Move cursor up and down for a bit
4. Stop moving mouse and left-click

Expected result: red timer does not reset to 0 after a mouse click
Actual result: red timer resets to 0 after a mouse click

Reproduced with: 2019.2.12f1, 2019.3.0b10 (input system preview.1 - 1.0.0), 2020.1.0a12 (input system preview.2 - 1.0.0)
Could not reproduce with: 2017.4.33f1 (no Package Manager), 2018.4.11f1, 2019.2.0a1 ("ugui" could not be found error), 2019.3.0a1 ("InputDeviceCharacteristics" could not be found error)

Notes:
- not reproduced on Windows
- reproduced on both macOS 10.13.6 and 10.14.6
- reproduced on both touchpad and wired mouse
- the red timer resets every time the mouse delta has a value other than (0,0) (e.g. while there is cursor movement)
- the issue might require few tries before showing up, seems to show up more consistently if cursor-click happens just after the frame in which cursor was still moving before becoming motionless