a phantom onscreen keyboard appears that I cannot use

when I enable screen keyboard either thru a keyboard shortcut or via the universal access menu there is a transparent square where the onscreen keyboard should be. Clicking on it does nothing. I also tried building the latest caribou with the same result.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: caribou-antler 0.4.21-5 [modified: usr/lib/caribou/antler-keyboard usr/lib/python3/dist-packages/caribou/antler/antler_settings.py usr/share/dbus-1/services/org.gnome.Caribou.Antler.service usr/share/glib-2.0/schemas/org.gnome.antler.gschema.xml]
ProcVersionSignature: Ubuntu 4.15.0-34.37-generic 4.15.18
Uname: Linux 4.15.0-34-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.3
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sat Sep 22 19:16:13 2018
InstallationDate: Installed on 2017-05-16 (494 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: caribou
UpgradeStatus: Upgraded to bionic on 2018-09-01 (21 days ago)