Latest repro: Version 2020.1.0a1 (998f3306adcf)
Earliest repro: Version 2018.4.4f1 (5440768ff61c)

Repro steps:
1. Open any shadergraph or VFX graph
2. Create any node with an input field
3. Click outside of the node
4. Highlight the number in an input field using the left mouse button, starting on the left or right side, dragging to the opposite side, and ending outside of the input field
5. Release the left mouse button
Expected result: the number stays selected
Actual result: the number is deselected when the left mouse button is released

Notes: this only happens when you do this in an input field that you are not already editing.