Hello Carol!
Thank you so much for sharing both screenshots! I'm not able to recreate this on my end. I've created a course with two slides, the first slide is blank, and the second has a video. I've set the seek bar to show on both slides in the Slide Properties, but it's unchecked in the Player Properties. Still, I see the seek bar appear in both Preview in Storyline 360 and Review 360. Here's the Review 360 link.
Would you mind sharing which version of Storyline 360 you are using? I am using Storyline 360 (Build 3.50.24668.0).
If you'd like me to take a look at your project, you can share it in this discussion or a support case.
