Hey @tessercat,
What I’m seeing is actually the issue. In my laptop, your slider looks fine but not on the desktop Full HD screen so this could be an aspect ratio mismatch.
Please take a look at the screenshots in the secure note. Notice that on a small screen, the container of the slider is a short rectangle while on a large screen, it’s a long rectangle because the height is fixed. Your image’s aspect ratio is closely matches the small screen container’s dimensions but that’s not the case on desktop.
Try setting your BG Fit to Contain.

You can find that under the Slide Options

For more details about that setting, please visit https://www.themepunch.com/slider-revolution/slide-background/
If that doesn’t help, please give us the following information in a Secure Note.
- WordPress Login URL
- Admin level username and password
Thanks.