I have reported this nasty Maxnote issue many times and in several threads in the past.
I am really surprised that is has not been fixed for a very long time. It is still there in the latest version 18.104.22.16800 Official.
Basically, when I try to add a bookmark to Maxnote (by pressing Ctrl+D or the Maxnote icon) and click the drop-down menu to chose a location in my folders, the list becomes detached, and the save button disappears.
So, I cannot use the `Add to Favorites` function.