I have the exact same problem on my Hopper Duo. I usually start by using the voice command "Netflix." (Occasionally, the Google Assistant banner will respond with a message "Sorry, I am not able to search Netflix yet." This is a separate issue, though. When this happens, the command "Launch Netflix" will usually work properly.) When the Netflix app launches and I select a show to watch, the majority of the time I will get the slow percentage progress increase (1% at a time) until it reaches 25% and freezes there. At that point, I back all the way out of the Netflix app and go to channel 302 instead. Most of the time, this fixes the issue, and Netflix works flawlessly. Some times, I get the 25% issue when going to channel 302, and then backing out of the app and using the voice command to launch it fixes the issue. Go figure.