Nbconvert and voila no ipywidgets - jupyter

Question

we are currently using JupyterHub for our team of mostly non programmers. ( Zero to JupyterHub with Kubernetes).
We want to use voila to provide the notebooks as web apps. We have installed it on the server and it runs with a reverse proxy (jupyter-server-proxy), witch works fine.
However, Voila does not display everything from the notebooks. Markdown, HTML elements, normal output and plots (Seaborn) are displayed without problems.
Unfortunately, no ipywidgets are displayed. Instead, only an empty output is displayed.
I also tried nbconvert alone with jupyter nbconvert --to html with the same result.
This is what I get with voila:
Voila output
This is what I get with only nbconvert:
enter image description here
absl-py 1.3.0
aiohttp 3.8.3
aiosignal 1.3.1
alembic 1.8.1
altair 4.2.0
anyio 3.6.2
appmode 0.8.0
argon2-cffi 21.3.0
argon2-cffi-bindings 21.2.0
asn1crypto 1.5.1
asttokens 2.1.0
astunparse 1.6.3
async-generator 1.10
async-timeout 4.0.2
attrs 22.1.0
Babel 2.11.0
backcall 0.2.0
backports.functools-lru-cache 1.6.4
beautifulsoup4 4.11.1
bleach 5.0.1
blinker 1.5
bokeh 3.0.1
boto3 1.26.5
botocore 1.29.6
Bottleneck 1.3.5
branca 0.6.0
brotlipy 0.7.0
cached-property 1.5.2
cachetools 5.2.0
certifi 2022.9.24
certipy 0.1.3
cffi 1.15.1
charset-normalizer 2.1.1
click 8.1.3
cloudpickle 2.2.0
colorama 0.4.6
conda 22.9.0
conda-package-handling 1.9.0
contourpy 1.0.6
cryptography 38.0.3
cycler 0.11.0
Cython 0.29.32
cytoolz 0.12.0
dask 2022.10.0
debugpy 1.6.3
decorator 5.1.1
defusedxml 0.7.1
dill 0.3.6
distributed 2022.10.0
ecdsa 0.18.0
enbw-aop-client 0.20221027.1
entrypoints 0.4
entsoe-py 0.5.8
envs 1.4
et-xmlfile 1.0.1
executing 1.2.0
fastjsonschema 2.16.2
filelock 3.8.0
Flask 2.2.2
flatbuffers 2.0
flit_core 3.8.0
fonttools 4.38.0
frozenlist 1.3.3
fsspec 2022.10.0
gast 0.4.0
geographiclib 1.52
geopy 2.2.0
gitdb 4.0.9
GitPython 3.1.29
gmpy2 2.1.2
google-auth 2.14.0
google-auth-oauthlib 0.4.6
google-pasta 0.2.0
gravis 0.1.0
greenlet 2.0.1
grpcio 1.47.1
h11 0.14.0
h5py 3.7.0
HeapDict 1.0.1
idna 3.4
imagecodecs 2022.9.26
imageio 2.22.0
importlib-metadata 5.0.0
importlib-resources 5.10.0
ipykernel 6.17.1
ipyleaflet 0.17.2
ipympl 0.9.2
ipython 8.6.0
ipython-genutils 0.2.0
ipywidgets 8.0.2
itsdangerous 2.1.2
jedi 0.18.1
Jinja2 3.1.2
jmespath 1.0.1
joblib 1.2.0
json5 0.9.10
jsonschema 4.17.0
jupyter_client 7.4.1
jupyter_core 5.0.0
jupyter-server 1.23.1
jupyter-server-mathjax 0.2.6
jupyter-server-proxy 3.2.2
jupyter-telemetry 0.1.0
jupyterhub 3.0.0
jupyterlab 3.5.0
jupyterlab-git 0.39.3
jupyterlab-pygments 0.2.2
jupyterlab_server 2.16.2
jupyterlab-widgets 3.0.3
keras 2.10.0
Keras-Preprocessing 1.1.2
kiwisolver 1.4.4
libmambapy 1.0.0
llvmlite 0.39.1
locket 1.0.0
lxml 4.9.1
lz4 4.0.2
Mako 1.2.3
mamba 1.0.0
Markdown 3.4.1
MarkupSafe 2.1.1
matplotlib 3.6.2
matplotlib-inline 0.1.6
mistune 2.0.4
mpmath 1.2.1
msgpack 1.0.4
multidict 6.0.2
munkres 1.1.4
nbclassic 0.4.8
nbclient 0.7.0
nbconvert 6.4.5
nbdime 3.1.1
nbformat 5.7.0
nbtools 21.12
nest-asyncio 1.5.6
networkx 2.8.8
neurolab 0.3.5
notebook 6.5.2
notebook_shim 0.2.2
ntlm-auth 1.5.0
numba 0.56.3
numexpr 2.8.3
numpy 1.23.4
oauthlib 3.2.2
openpyxl 3.0.10
opt-einsum 3.3.0
oscrypto 1.2.1
outcome 1.2.0
packaging 21.3
pamela 1.0.0
pandas 1.5.1
pandocfilters 1.5.0
parso 0.8.3
partd 1.3.0
patsy 0.5.3
pexpect 4.8.0
pickleshare 0.7.5
Pillow 9.2.0
pip 22.3.1
pkgutil_resolve_name 1.3.10
platformdirs 2.5.3
plotly 5.11.0
pretty-html-table 0.9.11
prometheus-client 0.15.0
prompt-toolkit 3.0.32
protobuf 4.21.9
psutil 5.9.4
ptyprocess 0.7.0
pure-eval 0.2.2
pyarrow 9.0.0
pyasn1 0.4.8
pyasn1-modules 0.2.7
pycognito 2022.4.0
pycosat 0.6.4
pycparser 2.21
pycryptodomex 3.15.0
pycurl 7.45.1
pydantic 1.10.2
Pygments 2.13.0
PyJWT 2.6.0
pyOpenSSL 22.1.0
pyparsing 3.0.9
pyproj 3.4.0
pyrsistent 0.19.2
PySocks 1.7.1
python-dateutil 2.8.2
python-jose 3.3.0
python-json-logger 2.0.1
pytz 2022.6
pytz-deprecation-shim 0.1.0.post0
pyu2f 0.1.5
PyWavelets 1.3.0
PyYAML 6.0
pyzmq 24.0.1
requests 2.28.1
requests-ntlm 1.1.0
requests-oauthlib 1.3.1
requests-toolbelt 0.10.1
rpy2 3.5.1
rsa 4.9
ruamel.yaml 0.17.21
ruamel.yaml.clib 0.2.7
ruamel-yaml-conda 0.15.80
s3transfer 0.6.0
scikit-image 0.19.3
scikit-learn 1.1.3
scipy 1.9.3
seaborn 0.12.1
selenium 4.6.0
Send2Trash 1.8.0
setuptools 65.5.1
SharePlum 0.5.1
simpervisor 0.4
simplegeneric 0.8.1
six 1.16.0
smmap 3.0.5
sniffio 1.3.0
snowflake-connector-python 2.8.1
sortedcontainers 2.4.0
soupsieve 2.3.2.post1
SQLAlchemy 1.4.43
stack-data 0.6.0
statsmodels 0.13.5
sympy 1.11.1
tables 3.7.0
tblib 1.7.0
tenacity 8.1.0
tensorboard 2.10.1
tensorboard-data-server 0.6.0
tensorboard-plugin-wit 1.8.1
tensorflow 2.10.0
tensorflow-estimator 2.10.0
termcolor 2.1.0
terminado 0.17.0
terminaltables 3.1.10
testpath 0.6.0
threadpoolctl 3.1.0
tifffile 2022.10.10
tinycss2 1.2.1
tomli 2.0.1
toolz 0.12.0
tornado 6.2
tqdm 4.64.1
traitlets 5.5.0
traittypes 0.2.1
trash-cli 0.22.10.20
trio 0.21.0
trio-websocket 0.9.2
typing_extensions 4.4.0
tzdata 2022.6
tzlocal 4.2
unicodedata2 15.0.0
urllib3 1.26.12
usp.common.data 5.1.0
usp.common.util 0.0.1
voila 0.4.0
wcwidth 0.2.5
webencodings 0.5.1
websocket-client 1.4.2
websockets 10.4
Werkzeug 2.2.2
wheel 0.38.3
widgetsnbextension 4.0.3
wrapt 1.14.1
wsproto 1.2.0
xlrd 2.0.1
XlsxWriter 3.0.3
xyzservices 2022.9.0
yarl 1.8.1
zict 2.2.0
zipp 3.10.0
I already tried different versions of nbconvert and have Save Widget State Automatically on true.
Does anyone have an idea?