Not an Octopus problem. Run them both in windowed mode (I'm assuming you have to press ctrl+esc because you're full-screen?) and see if that fixes it. Also, as a general rule, set two things:

1) Server tab --> Options --> enable "Broadcast pausing whilst alt tabbed"
2) Server tab --> Sounds --> set up an easily recognized sound for both "Broadcast Pause" and "Broadcast Resume"

Those two settings will tell you by sounds if Octopus is broadcasting or not. If the WoW window loses focus, it will "ding" at you and let you know it, so you can correct the problem.

Hope that helps!