Problem with character meshes in Unity (exported from blender)

So i'm learning from Brackeys and Sebastian's Lague tutorial and got problem with character i made. In unity when i'm making prefab it got empty mesh as you can see 'pants'. In scene view when i'm marking pants it marks it correctly but when i want to move them it doesn't work at all. Hiding pants works fine too.How can i fix that? I don't have that issue with shield and sword. What am I doing wrong? Please help me.

 

@dytrychrafal
It's possible that you solved this problem already, but if not, please repost the pics.