Floodlight camera - no output sound

I bought ring floodlight camera 8SF1P7-BEU0 in November 2020. I had it installed at the end of March this year and it was initially all working fine. For the last couple of weeks there has been no sound if I activate the siren - the lights come on and the red light underneath flashes but no sound. I can also hear audio in live view but if I try to press the button to speak there is no sound coming out. Does anyone have some advice on how to fix this?