I have a TCL 65R625 Roku TV and a Onkyo TX-NR585 receiver. The TV is connected to the receiver via an ARC connection using an HDMI cable.
When I play any streaming apps on the Roku TV (e.g., Netflix, Hulu, Disney +, etc.) there is a very noticeable audio delay. (The image happens and ~1/4 of a second later you hear the sound.)
When I play media from other devices hooked up to the receiver (E.g., DVD player, Playstation, my cable-provider's DVR, etc.) there is no lip synch problem.
This means that the only issue is when the media is played on the Roku TV and transmitted to the receiver via the ARC connection. I have adjusted all the receiver settings per Onkyo's instructions but the problem persists.