In the past few days, I've been unable to add Netflix shows to the watch list (when I try to add a show, it does nothing). Tried deleting and reinstalling the Netflix channel but same problem is occurring. I'm able to add shows from other devices (like my smartphone) so seems like it's a Roku issue more than a Netflix issue. Haven't noticed issues with any of my other channels. Using the roku stick.
After removing a channel, best practice is to clear the Roku's memory by restarting it before reinstalling the channel. Did you do this? Without the restart you may not get a clean reinstall.
Restart via Settings > System > System restart (for Roku TVs: Settings > System > Power > System restart)