Slideshow module not working.
Can you post system info. It's in the Help>System Info menu?
Working here on 12.6.2.
2015 Mac 12.6.3
LRC slideshow module issue, I can select images for a slideshow from library, when in the slidehow module i get a prompt saying preparing previews when that is complete the screen goes black and the slideshow does not start.
Worth a try, often fixes such oddities:
Try resetting your Lightroom preferences:
Also see: https://community.adobe.com/t5/lightroom-classic-discussions/important-steps-for-manually-resetting-...
Quit Lightroom Classic.
macOS: Press and hold the Shift + Option keys.
Windows: Press and hold the Shift + Alt keys.
While holding down the keys, launch Lightroom Classic.
When asked, select "Yes".