watchtv.cox.com web app will not play rented HD videos in HD

I've been having quality issues from this web app when trying to watch rented videos on the go, or even HD channels in general through this specific app. However, I have not had issues using channel specific apps such as Scifi, AMD, or HBOgo. They seem to play their HD components very well.

I'm not really sure why. I've tried playing the HD movies on another pc, through Chrome, Firefox, and Microsoft Edge. They are all very low quality despite the movies and channel being labeled as HD. And idea?