The output of my Euclidean distance from Roads seems to show the calculations only until the last feature ot the bottom. The process extend goes on though, but shows wrong values. It should get brighter instead of being dark (like on the other sides)

With dark beeing close to roads and bright further away.
What did I do wrong/ Do i have to do to get raster values to the full extend of the processing extend?
Note:I got this feature (mainroads) by deleting some other features (sideroads) from the original feature (main and side roads). The above mentioned problem does not occur with the original feature.