As mentioned in the documentation for 5.0, if you package a project you must run the .exe with these flags to start the remote control http and websocket servers:
-RCWebControlEnable -RCWebInterfaceEnable
I was using Remote Control Presets and I found that I also had to drag the actual preset into the scene as an actor, otherwise it was not available in my packaged game.
Finally, I was not able to actually change any properties of the preset when using the Remote Control API in a packaged game; the control preset existed, the properties were there but attempting to change them resulted in an error saying the property could not be updated. I noticed (when calling the remote/info endpoint) that there was no “ActivePreset” but I don’t know how to set that, and I don’t know if that would make a difference. (In the documentation it states that there can only be one active preset at any time)