There are additional problems:
If using the YouTube for televisions app on a new device, OR if resetting the app using the app's option under Settings, when using a "brand" account:
- Watch history no longer tracks or updates globally
- Search history does not show up, only top searches, although anything you search for will reflect on myactivity.google.com for the brand account.
This affects all versions of the YouTube for televisions app (Roku, Fire, Playstation, Smart TV). The YouTube app for Apple/Android is different. YouTube.com is different.
(This is even when using Google's DNS.)