As much as their names may make it sound, Import Accounts and Export Accounts are in no way built to transfer between ClearPass for migration purposes. They are there solely to import from some other system that can create a csv, or to export to another system as a csv with the specific fields you want. There are tons of backend fields and flags we have that are excluded from Export, plus the security measures on password mentioned above. The supported migration is simply a backup/restore from CPPM. If you need to continue with this path ensure you enabled enough fields in guest_export.