LaTeX.org

Many thanks for the advice. The problem turned out to be the use of \flushleft before the main text.

I have a document written in English, which Latex refuses to hyphenate, for unknown reasons. Interestingly, I have another document with exactly the same preamble, which is perfectly hyphenated. The preamble is given below.

\documentclass[parskip, a4paper, DIVcalc, 12pt, listof=totoc]{scrartcl ...