This looks like a recently-added warning, part of Live Update changes. We exclude Liveupdate from the manifest if that’s any clue.
Yeah, perhaps it’s something we want to silence. I wouldn’t think that the http loader would be disabled in your case as it’s new symbols used for the manifest.
ANd the http loader is still useful when loading from the editor (it’s used for hot reloading), so it’s a bit strange imho. I’ll double check.
In this case though, the warning corresponds with the built game failing to run.
I have the same problem, but I don’t use spine and live update