Hello! After months of research and watchin tutorials I wasnt able to solve my shadow problem. Thats why I’m looking here for some help by friendly people 
Problem description:
Shadows are disappearing on distance.
Check screenshots 1 & 2 please.
Light setup:
Directional Light (1x)
- Stationary
- details: screenshot 3
Sky Light (1x)
- Stationary
- details: screenshot 4
Building:
-Static object
-Lightmap density: blue - green
Rendermethod:
GPU Lightmass
Thank You so much for your help! Have a nice sunday!