If I enable shadow cast in 3d viewer, it is always on. There is no simple way to turn the accumulated shadows off.
If I enable shadow cast in experience builder, a "clear analysis"-button appears in the dialog box. This removes the shadows.
I think this must be some kind of an error?
3dviewer:
https://bodo-kommune.maps.arcgis.com/apps/instant/3dviewer/index.html?appid=8efe171f937c44d289c38ecd...
Experience builder (very rough setup, but illustrates the difference):
https://experience.arcgis.com/experience/37addc3a2fd94d1da416abf5bd89c971/page/Page/