When I press the voice command button, all I can hear is the little buzz sound, which can normally be heard when the voice commands are disabled for some reason. This time though, it happened everywhere and everytime on the circuit, when I tried using voice commands.
This happened on Career mode, and the problem didn't go away by moving on to another race weekend. However, the problem went away by restarting the game. It's still slightly frustrating, if it happens in the beginning of a 100% race(like it did with me).
The problem started, when I tried pressing the voice command button(multiple times), when my race engineer was talking, answering to my old command.
I just tested in a practise session if it happens every time similarily, but it didn't, so I suppose there's something else to it than just spamming the voice command button