Help Voice Command for apps

[spot01]

Hi hope someone may have an answer for this

I have Voice command for apps switched on and have the ticked for answering incoming calls, I also have S Voice set to continuosly monitor(bit of a drain on my battery I'm sure) but whenever I have an incoming call I can neither Accept or Reject using the voice command

 

[spot01]

would appear you have to go into Settings > Sound and uncheck sound & vibration