Mesh is black on Phone

i have a 3d character with default shader. i have a directional light. it is ok on editor scene and game viewport.when i deploy it to phone mesh is completly black. what can cause this?

having similar problems with one iPad build, looks like mesh is somehow inverted or goes transparent / black…
tried mono/il2cpp, optimize mesh on off, different ios versions, mesh normals are fine, and everything is good in editor.

so far only happens in 1 project, others models & projects are fine…

i found problem. i set tangents as calculated instead of import. it works now.