It will only shows "Creating Panorama Preview" and never finishes. This happened after the latest update. I'm at 2015.9 release.
What is your OS? I cannot confirm that behavior using my Windows 10 computer with Lightroom CC 2015.9.
I should have tried rebooting before ********. The issue went away after rebooting my computer, which is running W10. It's the first time I ever had a hard bug like that after an upgrade. I clearly should have done some very basic troubleshooting practices... thanks for the reply.