"1. Connect HDMI (ARC) IN on you TV with HDMI (ARC) OUT on your receiver. Do not use optical cable. Done that
2. Go to Settings > System > Control other devices (CEC) and enable "HDMI ARC". Done that too
3. Go to Settings > Audio > S/PDIF and ARC and select the audio format that works for you. Even though "Autodetect" is recommended, you might want to explicitly disable Dolby Digital Plus by selecting "Dolby Digital, DTS" (without +).
DTS? I believe TCL 55R617 does not support DTS but does support DD. Btw, now I can't even watch anything via receiver to TV. I found a temporary solution. I connected ARC out from receiver to HDMI1 from TV.
I will try to do what you say retarding selecting DTS as oppose to auto select without the (+).