First off, no chance you can use Android's built-in debugging? More info here:
https://developer.chrome.com/devtools/docs/remote-debugging
Wondering if there's something different about the environment. Like, you can't use XHR. Or JavaScript! Sorry, don't know anything about MRAID or MoPub.
Another option is that weinre for some reason can't find it's script tag, to figure out where the server is ("foo:8080"). Usually the server is determined by looking for the script tag for the target script. You can override this with globals:
* WeinreServerURL
* WeinreServerId
The `WeinreServerId` is the hash bit on the URL. Defaults to "anonymous", and you're not using it, so you shouldn't need to set it to anything.
Also try adding --verbose and --debug to your server startup, and perhaps you'll catch some kind of error message, if it actually connects but then later dies for some other reason.