Unable to delete import/export mapping

On attempting to delete an Import/Export mapping having pressed the Delete button on the pop-up warning, the dialogue fails to respond and seems to continuously load without deleting the Mapping.

I have recreated on d46 demo, this works on Master.

To recreate on Demo:
1. Import data (e.g. Contact) and Select fields for mapping
2. Save field mapping
3. In the CiviCRM administration area go to System Settings >> Import/Export Mappings
4. Delete the mapping

This is possibly related to the following issue: https://issues.civicrm.org/jira/browse/CRM-18984