No Shadows from foliage on landscape after stationary light build?

so i have this not too large landscape with grass painted on it using foliage tool. I’m using stationary spot lights at few specific dark places which lacking reach of direction light but after build foliage not creating any shadows from these spot lights.
since light build takes too long ,so for the sake of experiment i tried similar scenario on new level and shadows just building appearing fine here. Why is it not working on that particular landscape(or level idk).??

ok changing spot light to movable works but why stationary doesn’t ? pls help