I can assure that Comcast has correct codes which will allow an X1 remote to control an LG OLED. Did you program the remote?
Have you read and followed the information available here: https://www.xfinity.com/support/remotes/
My new LG OLED 55" 4K tv wont power on or off, nor does volume control work on my X! voice remote?
I have escalated your issue to the Comcast Team available to these forums. Check back often for a reply in this thread or via Private Message from a Comcast Official Employee.
I can help further investigate this issue. I can also have another one shipped out for you if needed and if the options is available in your area. In order assist you, please send me a private message verifying your first and last name, the phone number, street address, and the account number associated with your services.
To send a private message click on my name "ComcastChe", then click private message me.