Can't select "Settings file" for maven build step in free-style project

On a free-style project where I have a maven build step (Invoke top-level Maven targets), the Settings file selecting doesn't work. Whatever I select, when I return to the config page "provided settings.xml" is selected with no Provided Settings chosen. So I can't switch to default settings.xml, not can I select one of the provided settings.xml.

I'm fairly sure this did work with a pre-2.7 version of the plugin. I have been able to select a provided settings.xml in the past.