Lightroom no longer shows Quicktime MOV files in Mac

[kwcalm]

Lightroom version:  9.2.1

Mac OS X  10.13.8

iMac Pro (2017)

In the past, I could click on a .MOV video, and it would play in Lightroom.

This feature is gone. I can't play any videos in Lightroom.

All I get is a black video player screen. If I click on the 'play' arrow, nothing happens.

If I locate the video in the Finder, and double-click on it, the QuickTime player WILL play the video.

Is there a problem with Quicktime integration with Lightroom.

Any known issues?

Thanks.

[kentdesign]

First steps: TRY to  restore Lightroom preferences using the Method 2 mentioned in this article How to set Lightroom preferences