Comment 2 for bug 1853906

This problem occurs when attempting to deploy Ubuntu 18.04, too.

It appears that the ESP's \efi\boot\bootx64.efi is Shim. There's also a copy of fbx64.efi in this directory, but it looks like this Shim isn't configured to look for it, so in the absence of grubx64.efi in this directory, the boot process hangs when Shim is launched. At least, that's my hypothesis.