Universal Media Server | Forum

I've used BubbleUPnP with UMS for streaming to a Chromecast without problems. I don't know why you've installed BubbleUPnP-Server though, as far as I know that is another media server just like UMS. The question is how UMS comes into play at all in this setup.

You certainly don't need BubbleUPnP-Server for this, and I would try uninstalling it and see it that helps.