Hi Hal Hauk,
Thank you for reaching out gluu support , I will assist you on this ticket , please let me know which document are you following for creating the custom attribute. Hope you are following this,
https://gluu.org/docs/ce/4.0/admin-guide/attribute/#custom-attributes
Also can you please tell me which backend are you using couchbase or opendj.
Thanks and Regards
Mohit Mali