[Andrew Noon]

I just ran in to the same problem and for me after reading this forum it was an easy fix. What I did was opened Compressor. Then went to Compressor>Reset Background Processing… My Internet Sharing was already off as some people previously mentioned to try. I went to System Preferences, then under Internet & Wireless, clicked Sharing, then deselected Web Sharing. I have no idea if deselecting Web Sharing contributed to fixing the issue. But this is what worked for me. I also deleted all of the project history in the compressor. Again, not sure if that contributed, but the whole process worked. I would suggest initially trying the Reset Background Processing, then go from there if that doesn’t fix your problem.

Thanks so much to everybody who commented in this thread, you are a huge help!