i have such a problem - no sound from central channel from time to time.
i think there is some problem with lpcm output from ATV4K or HDMI handshaking with HD621.
after some manipulation all is ok, but after HDMI cables reconnection the problem comes back.
i have no algoritm to fix this bug. sometimes changing MD1 to MD2 helps, sometimes HDMI extractor on/off helps. are you using a HDMI cable that is supporting the latest specs? if not changing it might help.
861v4/ID40, G98, UHD722, Mark and Levinson No. 29, 2 * Linn LK85, Linn LP12, Musical Fidelity X-LPS v3, Empire Vandenhul MC1000, NVidia shield, PS4, Thiel CS2.4, Thiel 1.6 rear, Audio physic Celcius centre, Rel Quake Sub
| 
Google Search
|
Meridian Systems
|
Meridian Streaming
|
Restaurant
|
WiKi
|
Duncan's Meridian Info
|
Board Rules
|
Restaurant Rules
