Sky sphere broken (4-27)

Hello and please forgive me, I’m not sure, if this is the right place.
I was messing with the sky sphere, weather and day night circle. Now whenever I open the editor I get this message
Failed to load /Game/OpenWorld/_my/_material_new/MP_global.MP_global Referenced by M_Sky_Panning_Clouds2
Failed to load /Game/OpenWorld/_my/_material_new/MP_global.MP_global Referenced by MaterialExpressionCollectionParameter_0
and even if I start a new project my sky is without clouds. I´m not really sure how I messed it up and how to change it back to normal again. It would be nice if someone could help me

Try verifying the engine from the launcher: