HR_7348_ASSIGNMENT_INVALID when Assigning Payment Methods via API

We're assigning Pay Methods to an Employee via the API hr_personal_pay_method_api.create_personal_pay_method.

However, while most complete successfully, we're getting errors on a few records. The SQLERRM error message is "HR_7348_ASSIGNMENT_INVALID".

Out of 766 Records, 292 of these are having these issues.

Sample of the API is below (Note the Comments):

declare    cursor  pymthd_cur is    select  *    from    CUST_PAYMETHODS_INT                                     -- Our Custom Interface Table    where   batch_name = p_batch_name    and     assignment_id is not null                               -- Records that have passed validation, have Assignment IDs Populated    and     status in ('New', 'Upload Error', 'Validation Error');        type typ_pymthd_cur is table of pymthd_cur%rowtype index by pls_integer;    pymthd_rec  typ_pymthd_cur;            l_personal_payment_method_id    number;    l_external_account_id           number;    l_paymnt_obj_version_number     number;    l_paymnt_effective_start_date   date;    l_paymnt_effective_end_date     date;    l_paymnt_comment_id             number;        l_error_message                 varchar2(4000);    updated_rec                     type_pymethod_int;    l_success_count                 NUMBER := 0;    l_err_count                     NUMBER := 0;    l_debug_info                    varchar2(100);begin    open    pymthd_cur;    fetch   pymthd_cur    bulk collect    into    pymthd_rec;    close   pymthd_cur;    l_debug_info := 'Pass the interface to the API';    dbms_output.put_line(l_debug_info);