Creating new encrypted Drive with swap and root crashes installer

I was installing Ubuntu 16.04 in a VirtualBox VM.

I have set up following partitions:

- /boot as ext4 with 250mb
- the rest of 10GB as encrypted drive

I deleted the preset partition in the encrypted drive to create a new partition table.
There I set up the following partitions:
- swap with 2048MB
- the rest of disk space is allocated to root

I checked all formatting checkboxes and tried continuing.

After that I sometimes get to see the localization part but not always.
The installer crashes at some point from there on.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubiquity 2.21.63.4
ProcVersionSignature: Ubuntu 4.10.0-28.32~16.04.2-generic 4.10.17
Uname: Linux 4.10.0-28-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.10
Architecture: amd64
CasperVersion: 1.376.2
Date: Wed Oct 11 10:52:42 2017
InstallCmdLine: file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash --- maybe-ubiquity
LiveMediaBuild: Ubuntu 16.04.3 LTS "Xenial Xerus" - Release amd64 (20170801)
ProcEnviron:
 LANGUAGE=de_DE.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)