Business Partner # cannot be the processor

Hello,

I am having an issue with Business Partners not showing up on the Persons Responsible drop down in transaction NOTIF_CREATE. I have made sure that the partner has been created in transaction BP and that the Employee role BUP003 has been added into each user. I have about 57 users inputted into the system but only 30 are showing on the drop down. Can anyone tell me what I am doing wrong? Any help would be greatly appreciated. Thank you!