Audio through OWC Thunderbolt 2 Dock OWCTB2DOCK12P

I have a new MacBook Air (M1, 2020). [Replacing my 2015 MacBook Pro.]

I have an Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 adapter plugged into it.

Thunderbolt 2 cable between the adapter and an OWC Thunderbolt 2 Dock Model #OWCTB2DOCK12P.

I have a couple of USB drives plugged into the dock. Copy performance seems much slower than on the old MacBook Pro.

USB Wireless dongle for mouse and keyboard plugged into the dock is working fine.

4K TV plugged into the dock by HDMI displays video fine, but does not play audio.

Anyone have suggestions on how to get the audio to play? System Preferences: Sound: Output shows the TV's V405-H9 HDMI sound output, but when that is selected, the TV does not play sound. This worked in Big Sur on the 2015 MacBook Pro. I'm not sure if the root cause is in the dock or the thunderbolt 3 to 2 adapter.