Profile manager on the volunteer tab offers only "remove profile" button initially

Steps to reproduce:

1. From Manage Events, click Configure > Volunteers for an event which does not yet have volunteering enabled.
2. Check the "Enable Volunteer Management?" checkbox.
3. Note that beneath the profile selector, there is one button: Remove profile. This is not the correct behavior.
4. Click "Save" and wait for the page to reload.
5. Note that beneath the profile selector, there is one button: Add another profile. This is the behavior we want to see in Step 3.