conda kernels and conda modules not found in jupyter notebooks when added, but otherwise existant?

Question

There are many questions like this (e.g. Conda environments not showing up in Jupyter Notebook, Python: modul not found after Anaconda installation, https://askubuntu.com/questions/1271137/importing-anaconda-libraries-not-working). I have tried their solutions but to no avail.

In short, I have conda installed. I have installed jupyterlabs and nb_conda_kernels in my base environment. When I create a new conda env via a file, the environment is not listed in jupyter automatically. I can add it via

python -m ipykernel install --user --name <env-name>

but then after I restart jupyter and switch kernels, when I try to import a python module from it, it says module not found.

What do I need to do to fix this? I do not want to add jupyterlabs to every env.

NOTE:

• when activating the env in the terminal the path is correct, e.g. /opt/anaconda/anaconda3/envs/<env-name>/bin
• when using the env in the terminal, the pack is there.
• when using the kernel in Jupyter, the module is not there.