"delivers the output signal to the HDMI ARC and digital optical outlets."
That should be "or" and not "and".
HDMI ARC is full of misfires and flaming posts on the web. Optical should be fine so try it without the HDMI to the 450.
I have an LG 43UJ630V connected to a Samsung HW-K450. The firmware is up to date.
At first glance, the issue would appear to originate from the soundbar, but I'm almost certain the fault is with the TV and the way it processes & delivers the output signal to the HDMI ARC and digital optical outlets.
Here are my symptoms:
When the TV is turned on, the audio sync is excellent. No AV settings needed, no delay on the soundbar. Perfect.
However, over the course of a few hours the audio slowly begins to go out of sync. It gets worse and worse, until I'm forced to take action because it's so intolerably bad.
When it gets this way, AV sync settings for some reason cannot fix it. If I set the delay on the soundbar, it may temporarily correct it, but because the audio latency goes up and down over time, it's not a permanent fix by any measure.
When the soundbar is turned off and it defaults to the internal speakers, the delay seems to disappear.
I could leave the soundbar disconnected for 10 minutes, but as soon as I reconnect it, the issue returns.
However!!! - If I leave the soundbar connected and simply turn off the TV and back on again, the issue is resolved... until it slowly returns an hour or so later.
This would suggest the soundbar is not at fault here - the LG TV is.
Watching TV the last few days has not been a relaxing way to unwind at the end of the day. It's a chore, headache-inducing and incredibly frustrating.
I'm 99% sure the issue is with LG's product, and am encouraged by seeing so many others post about similar issues regarding the audio sync.
I haven't come across a single case though like mine, whereby the audio drifts slowly out of sync over the course of hours.
I've tried turning off all the potentially intensive/processor-hungry picture settings, forcing PCM output and everything else practically.
My guess is it might be resolvable with a firmware update, considering the success of a recent firmware update which resolved a similar issue for a different range of LG models, but how long should I wait until I give up and send it back?
Any advice or ideas are welcome.