Since i switched to 4.26 my landscape / material has dissapeared - Help Please

I have tried going into landscape, resample and apply but that doesn’t work.
Everything was fine until the update from 4.25 - 4.26.

I have also checked a second map and that landscape is the same. All black and white boxes on the landscape and the water has dissapeared too. Everything else has stayed the same, for example buildings, foliage etc.

All files are in the correct places in the content folder, nothing is missing.

Be great if someone can help out.