Unfortunately sometimes it is not so easy to bring KNIME and python together. There are some lengthy discussions in the forum (cf. below).
What sometimes worked for me was not using the .bat script but pointing directly to the python.exe (although it is not recommended by the ‘official’ guide)
As of now I have not brought together all the hints into one article.
Please note: some important packages like scikit-learn are not included in the yml file but you could install them via Anaconda.
So it is some trial and error. Also I am not 100% happy with Anaconda. Sometimes installations get corrupted or Anaconda messes the versions of packages up and would not be able to automatically repair it. So I had to reinstall the whole thing.
Another point. Sometimes it seems components of R or Python do not like long and complex paths. This should not be the case but it is in the real world.