I have this on my screen right now - The task bar shows the missing files window, but selecting it doesn’t bring it to the front - also cycling with alt-tab doesn’t bring it to the front.
I started with a montage with four files, copied the montage into a directory with four different file waiting, renamed the montage and then double-clicked it - the missing files window was written on top but immediately vanished. Wavelab opened full-screen as it was last used, but I can’t reduce it because it hasn’t got focus, even though the missing files window is behind it. I can open other montages from the taskbar’s right-click menu, but they all remain unresponsive, and the close command is also ignored.
Paul