Bridge not showing thumbnails for video files

I'm using Bridge CC 2019 v 9.0.2.219 on a iMac (retina 4k, 21.5 inch, Late 2015) running MacOS Mojave Version 10.14.2

and

the same version of Bridge CC on a MacBook Pro (Retina, 13-inch, Early 2015) running MacOS Mojave Version 10.14.3

With both computers, Bridge does not display thumbnails for video files - just the application icon.  This makes Bridge fairly useless to me.  Is there a solution to this problem??

File types impacted are:

.mov

.m4a

.mp4

.m4v

.mkv

I have tried purging the cache, restarting, etc.

Please help if you can!  I want to be able to sort all of my video files across multiple folders by date and be able to see what they are by the thumbnail.

Thanks.