An update:
I replaced my Roku stick with the Express 4K+. During the Roku installation, I was able to verify that every part of my system (LG UHD TV/Sony receiver/Roku) is now running 4K/HDR10/60Hz. I reran the Apple TV video troubleshooting feature and it said everything is fine.
That resolved some issues. Nearly all the other 4K movies that previously played in HD are now streaming as 4K. However, the specific James Bond films I mentioned above continue to stream in HD, not 4K, and that's clearly a problem on Apple's side that can only be fixed by Apple. I let them know three weeks ago, and of course they have yet to fix anything.
Final update.
After continuing to go back and forth for another couple of months, Apple customer service sent me this message:
Our team let us know that the iPad registers on our end as a high peak bit rate device, which would explain the movies appearing in 4K when it was tested out then.
The Roku displays as low peak bit rate device, which means that there are times when the device may be limited in processing high-quality video or large data transfers. This can reduce video quality and even cause buffering.
Thank you for all of the testing and the information that you’ve provided.
All of this conveniently ignores everything I reported to them. What a waste of time their customer support is -- yet another reason to keep avoiding Apple products. Clearly, atc98092 , you were right when you said:
Personally, I think this is another case of a provider "crippling" the performance of a competing device. We know for a fact that Apple will stream videos at a higher bitrate (possibly higher quality) to an Apple TV device over other devices. Similar to Google taking functions out of their app/channel for Roku devices that are available on Chromecast devices. And Amazon has some things that just work "better" on a Fire TV.
