ipyleaflet: ipyleaflet does not work in jupyter lab - "Error displaying widget: model not found"

After having failed to get ipyleaflet to work from the released packages I decided to try installing from the current git repo master branch.

Oddly if I run juptyer notebook then the maps do render correctly.

To create clean environment:

git clone https://github.com/jupyter-widgets/ipyleaflet.git
cd ipyleaflet
pipenv shell
pipenv install jupyterlab
pip install -e .
jupyter nbextension install --py --symlink --sys-prefix ipyleaflet
jupyter nbextension enable --py --sys-prefix ipyleaflet
jupyter labextension install @jupyter-widgets/jupyterlab-manager

Versions:

python --version
Python 3.6.7

jupyter lab --version
1.1.1

jupyter nbextension list
Known nbextensions:
  config dir: /home/xxxxxx/.local/share/virtualenvs/ipyleaflet-ot3agPQM/etc/jupyter/nbconfig
    notebook section
      jupyter-js-widgets/extension  enabled
      - Validating: OK
      jupyter-leaflet/extension  enabled
      - Validating: OK

If I then execute a simple statement in a notebook after running jupyter lab

from ipyleaflet import *
m = Map(center=(52, 10), zoom=8, basemap=basemaps.Hydda.Full)
m

Error displaying widget: model not found

Browser console log has following errors:

Could not instantiate widget manager-base.js:273:32
    _make_model manager-base.js:273
    l manager-base.js:44
    s manager-base.js:25
    s manager-base.js:17
Error: "Could not create a model."
    n utils.js:119
utils.js:119:20
    n utils.js:119
Exception opening new comm default.js:1001:20
    _handleCommOpen default.js:1001
Error: "Module jupyter-leaflet, semver range ^0.11.1 is not registered as a widget module"
    loadClass manager.js:251
    _make_model manager-base.js:263
    l manager-base.js:44
    s manager-base.js:25
    L manager-base.js:19
    L manager-base.js:15
    _make_model manager-base.js:257
    new_model manager-base.js:246
    l manager-base.js:44
    s manager-base.js:25
    L manager-base.js:19
    L manager-base.js:15
    new_model manager-base.js:232
    handle_comm_open manager-base.js:144
    _handleCommOpen manager.js:59
    _handleCommOpen default.js:995
default.js:127:24

Any hints on what I should try next? Thanks