Hi @ashelton,
Thank you for reporting this, and sorry for the trouble it caused on your page.
I was able to reproduce this on my test site. When a Slider with a background color sits inside a Container that has a background image, the color shows correctly in the editor but disappears on the front end. Image and gradient backgrounds on the Slider are not affected, just as you described.
This is the same layering issue we have already fixed for Container backgrounds, and I have confirmed the same fix brings the Slider background color back. It will be included in an upcoming Spectra Blocks update.
We will post here as soon as the update is out. In the meantime, we truly appreciate your patience and understanding.
I hope this helps you move forward smoothly. If you have any further questions or need help with anything else, feel free to reach out.
Have a great day ahead!