Spark WebUI not opening from Extension for Local Big Data Environments nodes

Hi there,
I am running a workflow ↓ that was provided to us in our DS study program and it works fine.

However, from the Spark CF Learner and predictor node clicking on the link for the Spark WebUI nothing happens ↓.

Has anyone an idea of what could be the cause. I am running KNIME AP on Ubuntu 22.04.
Thanks :Kurt