By the way, sorry for not being very helpful.
There's a bunch of prefs worth trashing and reloading logic, it seems some things can get corrupted and whatever you do it won't work until you rebuild the prefs... last time I did it there were about four files.... eg. com.apple.logic type files.
Everytime you try something new, keep a back up of the files, but remove them from the prefs folder before you reboot logic, if you keep the window open you will see logic replace them when you quit. I feel in the past this has been a fairly reliable "Refresh" for logic in the event of big changes.
Have you made sure you're fully installed...legacy content etc...?
Do you still Run 7? I'm taking it you were prudent enough to keep the old life boat to hand? however seaworthy 8 might be for me / some I still have 7 and my dongle to hand in paid sessions.
I was thinking you could render anything in 7 that might be the cause of your migratory problem.
sorry if that's a load of old useless babble.