On mouse Down not firing for left click on Button widgets when using precise click

When using the left mouse button to click and drag a button, the on drag detected will not fire even when using precise click. This was not the case in previous versions of the engine (Works as expected in 4.16, issue appears in 4.17.1)

Regression: Yes

1. Download attached project
2. Open project
3. Play in editor
4. Click and drag on the button on screen

Result: The on drag detected does not fire off when using precise click
Expected: When using precise click the button would not consume the mouse input and the on drag detected would fire off when clicking and dragging