(Build 5584) - so I started Compressor and... maybe it is doing something. I don't know. There is no window or menu item I can open to see what is going on. The only change is on the Actions menu, which now offers me a Cancel Compressor choice. This has given me plenty of time to read the forums anyway
OK... I found a great post from Staff on how to resolve problems with Compressor: here in the Installation and Config on MacOS forum. It looks like it was broke and that post shows how to fix it.
