Sounds like a setup problem.

You need to set this up as two input configurations on the 975.
For TV input it should be set to Video Input: None and Audio Input: HMDI ARC
DVD Input (Mine is on Video) should be set to Video Input: HDMIx and Audio Input HDMIx where 'x' is the port you plugged your DVD into (e.g. HDMI3.
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975/7075/SMS-1
Aperion Verus Grand Towers & Bookshelves, Verus Forte Center, Infinity Surrounds, Ultra-X12
Oppo BDP-203, XBOX360, Xbox One
LG 65" OLED
RR2150 w/Klipsch SCR-2