Hello @Sommerregen,
now it works reliably! Thank you so much for your effort! 
Hi @anyway, thank you for your effort and reporting the issue, too! Great to hear it is working now 
One final question: Is it possible to hide the āAdvancedā tab too? It is only admin stuff in there, which I donāt want the user playing around with. This is mentioned here #411, but itās not explained how and where the āAdmin Pluginā tabs can be controlled. It is for sure not useful to write something directly into the core files of the plugin.