Pick Parent Class window for new blueprints does not properly list available classes on Linux

When opening the Pick Parent Class window on Linux, the expansion arrow next to All Classes does not properly extend to show all classes.

Workaround:
After clicking the arrow to extend the drop down (gray/filled in arrow), closing and reopening the class picker will show the full extended list.

Regression:
No - Parent Class Picker functioned normally in 4.10.4 on Linux

1. Open UE4 Editor (any project)
2. In the Content Browser, click the Add New button and select Blueprint Class
3. Click the arrow next to All Classes

Result:
The arrow changes to show it is expanded but the list of other classes does not appear

Expected:
Expanding the list shows all available classes to create a blueprint

Repro Rate:
3/3