That’s not an oled set I’m afraid. This has something to do with oled panels rather than it being an LG specific issue (although they do make all oled panels available in commercially available TVs). This issue has been confirmed on the most recent Sony Oled.
It seems that the core issue behind fixing this problem is you haven’t actually been able to reproduce it. This is leading to tweaks and updates indicating it’s fixed when, if you’d been able to test on an oled, you’d realise it wasn’t.
Obviously I’ve moved on from this device because of this issue so I can’t really help with any troubleshooting. I just wonder if there’s any poster on here lives close to Sam and might be able to allow him access to their Oled so he can get a handle on what the issue is?