We have received reports of imports through the API updating prospect status to true when those signup profiles were added as non-supporters.
As people sign up on a website and uncheck "Send me email updates," NationBuilder adds them to the database as non-supporters. When running an import through the API to update those non-supporters, however, NationBuilder changes the is_prospect status to true. Their email status remains opted out, but the database incorrectly portrays them as prospects.
Thank you for reporting this Lindsey. That is not expected behavior as prospects and non-supporters are two fundamentally different things. We don't have a timeline for this fix but will keep you updated. In the meantime, you can update the prospect status by batch updating a list.