Bit of a strange event and if no one else ever saw this then probably not worth investigating. I’m on macOS 15.7.7 on an M4 using NNW Version 7.0.6 (Build 7059). I was hiding a few windows of different apps in a row (I know, I know; instead of showing the desktop…) and suddenly got stopped at NNW which refused. I explicitly checked if it had focus, tried again, another error beep and nothing happened. It did minimize (yellow button). Just now when I came back to it to check the version number and tried again for the heck of it, it worked. So I don’t know what happened. Could there have been an invisible modal dialog? Which then apparently disappeared on its own, so not very likely. Hide is not a function I particularly need or often use, so it’s not very important to me. But it was strange.
Weird thing about MacOS. If you use Command-H to hide apps, it won’t hide the last visible app.