Problem with required fields inside the group

I am trying to set a text field within the group repeater as required, but this field keeps giving me an error when I try to submit the form, even though it is filled in.

[dipe_row]
[dipe_one_third]
[text* nome-cognome placeholder "Nome e cognome*"]
[select ruolo "Sei..." "Socio/a" "Coniuge" "Figlio/a" "Simpatizzante"]
[tel telefono-partecipante placeholder "Cellulare"]
[/dipe_one_third]
[dipe_one_third]
[text luogo-nascita placeholder "Luogo di nascita"]
[date data-nascita class:nascita-field placeholder "Data di nascita"]
[email email-partecipante placeholder "Email"]
[/dipe_one_third]
[dipe_one_third]<span class="pform etichetta-costo"><strong>Importo in €</strong></span>
[number single-price class:singleprice min:0.00 placeholder "0,00"]
[/dipe_one_third]
[/dipe_row]