Profile manager on the volunteer tab excludes any profile containing custom fields which extend the Volunteer contact subtype

To reproduce:

1. Enable volunteering for an event.
2. View the list of profiles available to be used with this project. Choose one – say, "New Individual" – but don't select it in the UI.
3. In a separate browser tab, do Administer > Customize Data and Screens > Profiles and modify the profile you chose to include a Volunteer field such as "Camera Skill Level."
4. Go back to your other browser tab which shows the Volunteer tab for an event and refresh the page. You'll find that the profile you modified no longer appears in the list.