Asset element removed from the list if the array size value selected while adding the element.

Steps to repro:
1. Create a new project.
2. File > Build Settings > Player Settings > Other Settings.
3. Optimization > Preload Assets > Add element by Clicking on "".
4. Select array size value > Add 3 element by Clicking on "".
5. Click outside the preload Assets section.

Actual Result:
Asset element removed from the list if the array size value selected while adding the element.

Expected Result:
Asset element should be added in the list.

Reproducible in:
2020.2.0a13.

Note:
Array setting is changed from 2020.2.0a13.

Environment:
Occurring on Windows 10 & Mac 10.15.