I believe Roku_Ads_util_getNoResponseFromUrl is just the name of the function that requests a URL where no response is expected (e.g., tracking requests). I don't believe it is indicative of no response being received. In fact, the URLs in those lines from the debug output would have been retrieved from the VAST response, so RAF is definitely getting a response.
With that said, if you look at the URL that's being called there, it indicates that video playback failed.. "&label=videoplayfailed%5BERRORCODE%5D"
Looking at the VAST response for the DFP url, it looks like it's only return Flash/FLV videos, which Roku does not support. You should configure it to return MP4 and/or HLS renditions of the ads instead.