Ubiquity crashed upon selecting format of ext4 partition

What I did: 1. Launch Kubuntu 17.10 Daily from live image (0309), choose to try out Kubuntu before installing.
2. Launch the installer from desktop.
3. Choose to manually partition the installation
4. Select to delete a partition (I formatted an ext4 part. with an encrypted home partition)
5. Create a new ext4 root-partition from the available space
6. Select to format the new partition - installer crashes with the message:

" Traceback (most recent call last):
  File "/usr/lib/ubiquity/ubiquity/frontend/kde_components/PartitionModel.py", line 66, in setData
    item.partman_column_format_toggled(value.toBool())
AttributeError: 'int' object has no attribute 'toBool'
"

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: ubiquity 17.10.4
ProcVersionSignature: Ubuntu 4.12.0-12.13-generic 4.12.8
Uname: Linux 4.12.0-12-generic x86_64
ApportVersion: 2.20.7-0ubuntu1
Architecture: amd64
CasperVersion: 1.384
Date: Sun Sep 3 12:13:22 2017
ExecutablePath: /usr/lib/ubiquity/bin/ubiquity
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/kubuntu.seed boot=casper maybe-ubiquity quiet splash ---
InterpreterPath: /usr/bin/python3.6
LiveMediaBuild: Kubuntu 17.10 "Artful Aardvark" - Alpha amd64 (20170903)
ProcEnviron:
 PATH=(custom, no user)
 LANG=nn_NO.UTF-8
 SHELL=/bin/bash
Python3Details: /usr/bin/python3.6, Python 3.6.2, python3-minimal, 3.6.1-0ubuntu3
PythonDetails: /usr/bin/python2.7, Python 2.7.13, python-minimal, 2.7.13-2
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)