Same problem for me. Also doesn't work through the website watch.spectrum.net. Even more concerning the watch.spectrum.net displays an email address that has nothing to do with my account.
I am also getting nowhere with the Spectrum TV app on my Roku 3. I get an error "RLP-1001" and have rebooted, updated, deleted, reinstalled, rebooted... no problems with any other Roku app, and no other problems with other devices on the network.