I updated to macOS High Sierra and now Xcode is suddenly saying an app's icons are totally missing when preparing for upload to iTunes Connect. This is an error returned by the iTMS service after the upload, not Xcode 9.
Missing recommended icon file - The bundle does not contain an app icon for iPhone / iPod Touch of exactly '120x120' pixels, in .png format
I exported the IPA locally and of course (and as expected) the icons are all there, as nothing has changed in that configuration since our last successful binary upload, which did not render this error.
To me this seems like an iTMS issue, but I have no way of knowing unless there's a workaround. Anyone know?