It’s probably thunderstorms. Global weather models CANNOT predict the exact location of future thunderstorms. Reason why the Radar layer is useful in these conditions. However you can see that thunderstorms have been predicted not so far from where radar displays rain. If you looked at the Thunderstorms layer, ECMWF was probably showing stormy conditions in the area.
Try using AROME in western part of Czechia. This high-resolution model is quite good at forecasting convective rainfall.