Just be patient
I lost "Recently Watched" after updating the software on my Apple TV. I called Netflix, but they were unable to help. They did not know if this was a glitch or a feature of the update. I tried completely restoring the Apple TV (including another download of the software) but that did not fix the problem. So I gave up and went to bed. The next morning when the Apple TV was turned on "Recently Watched" had returned. So given my experience and the comments above the best course of action seems to be no action, but rather patience, which is not the answer you usually want when your device is not functioning properly.