Weird. It doesnt look like that sun is generating any indirect lighting. You havent played with any lightmass settings in World Settings, have you?
To change the BP lights’ mobility, open up the blueprint(select one > on the right side World Outliner > click Edit Blueprint) and you’ll see the light in components list on the left side. Select the light and set it to Stationary. If this doesnt work either remove those BP lights and add a normal point light into the level and the rebuild the lighting.