Add Font Override Dropdown Acts Unresponsive to Mouseclick

When creating a new Sub-Font Family the user should be able to add a font to the Sub-Font by clicking the Add Font Override dropdown. The dropdown would then give the user the Font option.

However when tested in 4.14 and 4.13.1 The dropdown has proved unresponsive the majority of the time. The dropdown would only respond a couple of times, raising concern for the feature.

Setup: Open up a new BP project.

Repro:

1. Right click in the content browser and create a new Font asset under User Interface.
2. Open the Font asset and add a font under Default Font Family.
3. Add a Sub-Font Family.
4. Add a Character Range and font to the Sub-Font.
5. Click Add Font Override.

Expected Result: Add Font Override drops down to show the font option which can be added to the Sub-Font Family.

Result: Add Font Override is unresponsive to the mouse.

Frequency: 8/10

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