Since posting the query, I have been playing around with the TV. I did something and think the Region Selection is now gone. The morning after the change, frustratingly, it still appeared. However, I have not seen it since, which was 5 days ago. Please try this, and let me know if it works for you. FYI, I have a 7 Series.
3. Auto Tuning Settings
4. Standby Auto Tuning - turn this OFF
My TV had been set to Auto Tune 2 hours after turning TV off. My theory is that the fresh tuning is the reason the TV kept asking for Region Selection to be made.
Please do post what results you get from these changes.
Are you trying to disable the 'Sleep' and/or the 'Off' Timers?
If so, try as below.
3. System Manager
5. Sleep Timer or Off Timer - Turn OFF
Hope it works for you