Voice chat for fortnite on switch does not work?

I gave my son gamer headphones from turtle beach (ear Force RECON 70) so that he can talk to his buddies while playing fortnite. Now he can hear her but still can't speak to him. Have already tried to fix the problem via settings but without success. The Voice chat on / off field is not displayed in the settings, but only text chat on / off.

Did you also check whether Push to Talk is over? If not he can click on the friends list and press this microphone symbol, at the bottom of it he can select it!