Section background image set, but CSS outputs background-image: unset

Hi,

I’m facing an issue with Enfold / Avia Layout Builder where a section background image is set in the editor, but no background-image: url(...) is generated on the frontend.

What I see

• In the Avia editor, the section clearly has a background image selected
• The image attachment exists, has metadata, and wp_get_attachment_url() returns a valid URL
• _aviaLayoutBuilderCleanData contains the image data, e.g.:

src='https://example.com/wp-content/uploads/2022/02/example.jpg'
attachment='3172'
attach='parallax'

What is generated
In both per-page CSS (dynamic_avia/avia_posts_css/post-XXXX.css) and merged CSS,
Enfold outputs:

.avia-section.av-XXXX {
    background-image: unset;
}

The image URL does not appear anywhere in CSS or HTML.

Important detail
In the same builder data block, the section has:
background='bg_color'
even though src / attachment are set.

Question
Is background-image: unset expected behavior when background='bg_color' is set, even if an image is assigned?

If yes:

• what is the correct way to switch a section from bg_color to image mode programmatically?
• is there a supported way to make Enfold re-evaluate the background type based on existing src / attachment, without manually re-editing each section?

Specific case, you can see on this page:
https://skotakconsulting.cz/fuze-spolecnosti/

There is supposed to be a background image on the top section. Which is actually set in editor. You can see it here:

and here:

On that page, there is completely missing following section with parallax background image:
<div class="av-parallax enabled-parallax active-parallax" data-avia-parallax-ratio="0.3" style="top: auto; height: 827px; transform: matrix3d(1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 185, 0, 1);"><div class="av-parallax-inner main_color avia-full-stretch"></div></div>

Thanks for any clarification.

Vaclav