Skeletal meshes disappear when switching to android preview 4.21

I recently Updated my project to 4.21 everything was going fine from 4,20 until I updated

If I switch the preview rendering from shader model 5 to Android preview most of my human skeletal meshes become not rendered from the game
as I can tell this issue did not happen until I switched versions
my skeletal meshes only have 45 bones and barely get to 7k polygons
this issue seems to happen to my human meshes and not any other as I have animated weapons on the game
here I posted some screenshots