grub efi installer crashes when luks volume group is manually created before installation

[James Rivett]

I manually created a LUKS volume group so I could store my data and swap inside while booting 3 other operating systems on a Mid 2015 Macbook Pro. I first unlock the LUKS VG, then manually set the install partitions in the ubuntu installer. once the installer tries to install grub, it fails and crashes.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubiquity 2.21.63 [modified: lib/partman/automatically_partition/question]
ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
Uname: Linux 4.4.0-21-generic x86_64
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
CasperVersion: 1.376
Date: Thu Apr 28 17:44:12 2016
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/ubuntu.seed boot=casper quiet splash ---
LiveMediaBuild: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)