The question about Ubuntu was just speculation as to why you are getting a slightly older version of Jupyter Lab than Anaconda lists. I was wondering if you were using 16.04 or 18.04 and conda was noting something in it and keeping JupyterLab older based on that. But apparently that wasn’t it. Ubuntu should be fine.
Sadly I haven’t tried setting this up recently, and so I cannot confirm if I see the same thing or not.
Did you try running conda update jupyter and then run things?
Did you try running this:
conda install ipywidgets
conda install widgetsnbextension
And then try enabling and running it in the classic notebook mode?
And if that doesn’t help, try opening a notebook in the classic interface and running the following in it:
%pip install ipywidgets
%pip install widgetsnbextension
Then close the notebook session and run jupyter nbextension enable --py widgetsnbextension in your terminal. Then relaunch your notebook session and see if widgets work in your classic interface then.
Your slider code works fine when run in sessions launched form here.
I have no idea about ipyturtle but maybe if you figure out what finally gets the ipywidgets extension working right in your environment, you can try that approach with ipyturtle.