If you are unable to see the Volunteer Shift Worker fields while creating the "Sign Me Up" action, it could be because you are trying to create the action on the wrong object.
Make sure that you are creating the action on the Volunteer Shift object and not on the Volunteer Shift Worker object. You should be able to see the Volunteer Shift Worker fields once you select the correct object.
If you are still unable to see the fields, double-check that the Master-Detail relationship is properly set up between the Volunteer Shift and Volunteer Shift Worker objects. Check that the "Volunteer Shift" field on the Volunteer Shift Worker object is a Master-Detail field that references the Volunteer Shift object.
Once you confirm that the relationship is set up correctly, try refreshing the page and creating the action again. If you still have issues, try creating a new Volunteer Shift object and test the action on that object to see if the fields appear correctly.

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