I hope I don't jinx myself by sharing this, but my goal is to help others facing similar issues, saving them the frustration I've experienced — especially considering how much we invest in these devices.
After deciding to purchase another HDMI cable to test if a different brand could resolve the issue, I performed another power cycle test, this time slightly differently from before:
Turned off the TV, receiver, and subwoofer (though turning off the last one might seem unnecessary, I'll explain why shortly).
Unplugged all three from their power outlets.
Removed ALL HDMI cables from the TV — no exceptions.
Removed ALL HDMI cables from the receiver — again, no exceptions.
Waited 30 minutes (although it was closer to 40-45 minutes, as I took some extra time before actually start to count time).
Plugged the TV, receiver, and subwoofer back into their power outlets.
BEFORE turning anything back on, reconnected all HDMI cables to the TV first, and then the receiver.
Turned on the TV.
Turned on the subwoofer.
Turned on the receiver.
Went to the TV settings and switched audio output to HDMI.
Now, regarding the subwoofer: since the goal of the power cycle is (as I understand it) to completely clear any residual electricity from the devices, I concluded that the subwoofer might also have an influence.
The subwoofer in my setup is active, meaning it requires its own power source. Additionally, the connection between the subwoofer and the receiver involves electrical signals, as with any speaker. Testing it this way made sense to me.
After all this effort, surprise, surprise...
The problem persisted — and initially seemed worse, with the connection between the TV and receiver repeatedly dropping, causing rapid flickering between the "No Signal" message and the TV's volume meter popping up constantly.
At that point, I was ready to give up (again). Out of frustration, I stood there watching the screen furiously flicker.
Then, after a few intense seconds, the flickering suddenly stopped. The TV started displaying images correctly, and the receiver's front panel showed "DSUR", confirming that the handshake went well.
This occurred two days ago. Since then, I've experienced no more flickering, no random "No Signal" messages, and no frustrating audio dropouts.
My previous frustration (extreme annoyance actually) and hopelessness regarding LG's willingness to investigate the issue have finally eased.
I genuinely hope this helps anyone else experiencing similar issues. And if someone from LG is reading this, please consider such concerns seriously — even if issues appear extremely isolated.
Thanks for your time. Take care, stay safe, drink water, and hug someone next to you. See ya!