I just found the root of the problem. I used the CSS property “position” to arrange several radiobuttons and text in the “programnode.html” file, which seems to have caused the missing URCaps tab. I did not expect Polyscope to react that way to a misstake in the HTML file, especially since there is a post about an error occuring when having a HTML misstake/ unsupported HTLM code. → HTML Problem occurs
Maybe both topics can be merged since they share basically the same solution: Stick to the API docs!