ua enable fips fails on Ubuntu Pro

Hello,

'ua enable fips' errors out on stock Ubuntu Pro AWS 18.04 with a gpg error...

DEBUG: Failed running command 'apt-get update' [exit(100)]. Message: W: GPG error: https://esm.ubuntu.com/fips/ubuntu bionic InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY C1997C40EDE22758
E: The repository 'https://esm.ubuntu.com/fips/ubuntu bionic InRelease' is not signed.

Is there something I might have missed in the setup procedures?

#ua status
SERVICE ENTITLED STATUS DESCRIPTION
cc-eal yes n/a Common Criteria EAL2 Provisioning Packages
cis-audit no — Center for Internet Security Audit Tools
esm-apps yes enabled UA Apps: Extended Security Maintenance
esm-infra yes enabled UA Infra: Extended Security Maintenance
fips yes disabled NIST-certified FIPS modules
fips-updates yes disabled Uncertified security updates to FIPS modules
livepatch yes enabled Canonical Livepatch service

Enable services with: ua enable <service>

                Account: 5sniped9
           Subscription: 5sniped9
            Valid until: n/a
Technical support level: essential

# cat /etc/os-release
NAME="Ubuntu"
VERSION="18.04.4 LTS (Bionic Beaver)"
ID=ubuntu

Thanks,
Dan