No matplotlib plots in scientific mode

I am using PyCharm Professional (2020.1) on MacOS with a remote Python 3.7.6 interpreter (Anaconda). Unfortunately, matplotlib does not work properly: The plots do not appear in the "SciView" windows. plt.savefig() works properly, plt.show() does not. I do have Settings | Tools | Python Scientific | Show plots in toolwindow activated. That should not be a problem. In addition, when I access this same interpreter using same PyCharm version from my MacBook the plots do show. They didn't always (despite many reinstalls of PyCharm) but at some point they randomly started showing.

I have seen tons of threads on the internet - most from around 2018 - but none came to a satisfactory conclusion.

Does anyone have an idea?