Nopes, the random lenghts were checked. The funny thing was that the same text didnt broke down on the same word every time. With every site-refresh it would break down at different point. So the “bug” was dynamic, and thats why I couldnt find the “rule”, e.g. the cause of it. No matter if I had incresed the excerpt height – I would just get bigger empty space, without text being displayed.
Thank you, Mateja
