So far, I get a valid response from my Roku 4630X when I send the keypress/search command but nothing ever happens on any screen. All other keypress commands that I use work as expected. Is this function not implemented? If so, when can I expect it?
If you are expecting that sending keypress/search would navigate the UI to the global Roku search UI, as the SDK "External Control Guide" documentation would lead you to believe, that isn't implemented. The documentation is incorrect, and has never worked as described as far as I know. The Search key is now reserved for use with physical remote controls having the voice search function.
You might want to look at using the ECP search/browse command instead.