Integration won’t accept values for Single select fields

So far, this seems like a great plugin and works much better than the chronically flawed, unstable “official” Constant Contact plugin. The one issue I have encountered is that I can’t push values to Single select fields. I have a custom field in CC called ‘Professional Role’, and it has options like “Teacher”, “Researcher” and so on. If I pass the value “Teacher” from CF7, I’ll get this in my error log:

{"error_key":"contacts.api.validation.error","error_message":"custom_fields.professional_role 'Teacher' is not a valid value is required for custom field professional_role"}

This is the case whether the field on the WordPress side is a dropdown, a checkbox, or a plain text field. I can’t seem to get the value over to Constant Contact in a way that it will accept.