How can I set default value for a custom single choice field in Next Gen HRHD?

I have created a custom field using App Composer for a NextGen HRHD page. It's a single choice list with list of values. I am trying to set one of these values as default in the custom field. I have tried setting default value using App Composer itself and tried using VBS Default value field which also did not work. The field still does not get defaulted with the selected value and shows up as blank. (It allows to choose a value from the LOV but nothing gets defaulted.)

Any advice would be much appreciated!