Depending on the setlists you're importing, you may be running into the text element limit (which can cause crashing when loading a song or even when switching to that setlist, if you have too many songs on the list).
If this is indeed a setlist length issue, go watch this ExileLord video, and download the fix he links in the description. There's still a limit due to another bug, but it's much higher than the 80-ish songs most GH3 installations are stuck with. And I doubt the second bug will ever be fixed, as Exile has moved over to Clone Hero.
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