Hi @thekendog,
Thank you for reaching out.
The Kadence Advanced Image lightbox is handled by the theme. To enable lightbox for an Image (Adv) block:
1. Navigate to the theme Customizer > General > Performance
2. Toggle ON Enable Lightbox
3. Copy the Image File URL from your Dashboard > Media
4. Edit the page with the image and paste the URL in the Image Link
Here is a screencast of how to achieve this:
https://share.zight.com/jku85mqY
You can apply these settings to the Gutenberg Image block as well.
I hope this helps. Please let us know how we can help further.
Cheers,
Eze