why cant i use my libero ?

[2020 GANTI AKUN]

i have 1 libero player on my reserve players but i can make him starter on my carrer teams

[Moto]

In real world indoor volleyball rules, the libero is not set on the starting rotation. That's why the libero position is kinda "bench" but when you have a rotation with the libero in it, it'll show in the back row where it is supposed to. You can confirm this by remembering what the libero's jersey number is and you'll see it in the next few rotations in a game.