Most likely a question of Passthrough capabilities of the TV ARC.
Your TV reports this, while not clear which ones it can passthrough ARC
CodingType MaxChannels SamplingFreq SampleSize
PCM, 2 ch, 32/44.1/48/96/192 kHz, 16/20/24 bit
AC-3, 6 ch, 32/44.1/48 kHz, MaxBitRate 640kb/s
Dobly_Digital+/ATMOS, 6 ch, 32/44.1/48 kHz, AFCDepValue 0x1
DTS, 6 ch, 44.1/48 kHz, MaxBitRate 1536kb/s
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