Skeletal mesh's material works both in persona and when placed in the editor ( and in material editor) but when start play ( both pie and standalone) the skeletal mesh become default gray, any suggestion?

I have a characterBp, in its event graph when i press K key input thw BP chance his skeletal mesh trought The node “Set skeletal mesh” ( both skeletal mesh have the same skeleton). Some time ago this character works well But now when i press The K key it chance The skeletal mesh But his materiale become default gray ( i have noticed that behaviour after The upgrade from 4.20 To 4.22)