The window of "what's interesting" tool opens normally, but as soon as you click on the sky map, it goes in the background of the main window, as shown in the video. After a few manipulations, I manage to put "what's interesting" in the foreground, but some buttons (those below) are unusable. I close the windows of "What's interesting", I restart the tool, and there, miracle, everything works normally ... the problem seems to come from the fact that at startup, the tool opens a second window. When we close these windows and restart the tool, it does not open additional windows and then works properly. I made a screencast of the bug available here : https://youtu.be/C-6B_T8LQlA
This is also happening in version 2.9.2. First time selected and the second window opens and if closed you can reopen the What's interesting sidebar normally.