Everything disappears from timeline with a zoom region on it.

Hello Jim!

Thank you for sharing a screenshot with us! I've tried to replicate this on my end using the steps you've listed. Unfortunately, I'm not seeing the other objects disappear on the timeline when duplicating a slide with a zoom region, images, and a mouse interaction.

With your permission, I'd like our Support Engineers to take a look at your project. You can share your project with them in a support case. Your project will be deleted after troubleshooting.