Physic asset cover all mesh. Without it looks just awful blinking like a Christmas tree. Physical Asset partially solves this problem, but not everywhere. According to the documentation, that I understand, the physical asset affect the behavior only on the shadows not on light.
Anyway, found by such variant: in blueprint skeletal mesh installed inderect lighting cache quality set to ILCQ Volume and sample placement scale set to 1.
I do not much understand why it is works, but in fact that helps