At some point, support for Jupyter notebooks stopped working in IntelliJ IDEA. Notebooks are not being rendered, I can't find any Jupyter related configuration.
IntelliJ IDEA Ultimate - version 2023.3.2
Any ideas on what/where to check?
I'm having the same issue with the same version you are. Whacking/recreating venvs, reinstalling jupyter, etc. didn't help.
However, after contacting Jetbrains, they say they've now updated documentation that suggests you need to install the Jupyter plugin in addition to the Python plugin.
Link to documentation: https://www.jetbrains.com.cn/en-us/help/idea/ipython-notebook-support.html