Cannot play back any videos in Lightroom Classic 9.0

[weiqunl]

I have recently upgrade Lightroom Classic to 9.0 running on Mac OS X Catalina 10.15.1. I found that I can no longer play back imported videos any more. The play button is grayed out. If I locate the video file in Finder, I can play it with no problem. Please advise!

[cmgap]

Have you tried to purge your video cache yet?  Under Preferences  > Performance > Video Cache Settings > Purge Cache. Quit and restart Lr.

[weiqunl]

I did and it still doesn't work.