Ensure the Registration Types are available on the front end, as it is likely they are set to Sphere Only:
  1. Navigate to Communities>Forms>Registration
  2. Hover over you event and select Website Info
  3. Click Step 3 for Registration Form Options
  4. Scroll to Registration Type section and click Edit next to the Registration Type to made available online
  5. Select the Payment Information tab
  6. Unmark the box for "Sphere Only"
  7. Click Save
  8. Navigate back to the Webinfo Checklist and click Publish This Event Now