Why does testing fail with custom_field_1?

Testing does not work with custom_field_1. After spending multiple hours at night trying to figure it out, I gave up and went to bed frustrated. This is odd that "first name" works and custom fields do not. Please correct. In the meantime, to save other customers the anguish, add an information line to the testing section. Note, if you have it listed somewhere, it was not apparent (documentation does not count for things like this). Thank you.