Apple Car Play just installed on RX 350H but when prompted no response from Hey Siri.

 

What happens when you say Hey Lexus? That would rely on the in-car features, though.

Tried rebooting your phone?

Yesterday, our WAZE directions became 'silent'. (no audio) Haven't tried to determine why, yet. Don't like to mess with that stuff while driving.

 

Being an "is it plugged in" kind of person, I have to ask if Siri is enabled on your phone? I know I turned that feature off on mine.