Thank you for the quick answer and for reminding me to create a MWE. Working with that revealed that another package is breaking the behaviour, because your solutions does in fact not fix it inside my project. The offending package is
\usepackage{tocloft} \setlength{\cftfignumwidth}{3em} Which breaks it. But I need to to fix the width of the space allocated for toc-entry numbering. Any ideas?