grub is unable to chainboot from network to SATA drive

Machines which are managed by MAAS are configured to always network boot. When an operating system is deployed grub is sent[1] a configuration file which searches drives for recognized boot loaders. When the local disk is a SATA drive this process is not working. The config exits at the end to fallback to booting the next configured device but this config does not always exist(e.g LP:1906379). In that case the deployment fails.

I've verified this happens with grub from Focal(1.142.9+2.04-1ubuntu26.7) and Bionic(1.93.22+2.02-2ubuntu8.20).

Reproduction:
1. Create a KVM which uses an emulated SATA drive and UEFI firmware.
2. Add the machine and commission it in MAAS
3. Try deploying any operating system. CentOS 8 currently fails to deploy because it does not create a UEFI entry.

[1] https://git.launchpad.net/maas/tree/src/provisioningserver/templates/uefi/config.local.amd64.template