Background's missing after Pro 6.7 (conflict between theme and WP Rocket's "remove unused css")

[DieSEAExperten]

Hi,

you must have changed something significant between Pro 6.6.10 and 6.7.0 (and all following releases) regarding backgrounds. It’s also somehow written in the changelog (“Feature: Background layers has breakpoint support”, “Feature: Background image background-attachment controls”)

Sadly right after the update on August 5, 2025 our site was broken: many background images where missing or background colors where showing as white on frontend.

I immediately reverted back to a backup and used the last month to slowly work my way through the troubleshooting on our staging site. Today I can say: The problem is related to Pro 6.7.0 and WP Rocket’s “remove unused css”. When using the feature on your 6.7.X css like

 .mqw-9.x-section {
    background-color: #173952;
}

are missing and that is causing the sections to appear white on frontend.

I do know that WP Rocket’s not your business and you will recommend to hire your service Boost but WP Rocket did not change anything on their end recently. Everything was (and is when downgrading) working flawlessly for years until your update. For now all my projects are stuck on Pro 6.6.10 and that’s sad. So any other other suggestion than stop using WP Rocket’s “remove unused css” or hiring Boost is welcome! Do you have any idea what could have caused this? Must be a bigger change in the background then just adding some toggles for responsiveness?

I am wondering if somebody else has reported this issue? Thank you

[charlie]

Have you tried a later release besides 6.7.0? We have a number of fixes around this in the point releases. If that doesn’t work do you have a site we could look at?

[DieSEAExperten]

Thanks @charlie! It’s sadly with various versions, staging is up to date. You can find it in secure note.

[charlie]

Which part has missing background images and could share some site login details?

[DieSEAExperten]

It’s not only images but also just colors. Some screenshots attached. And login in secure note.

[prakash_s]

Hello @DieSEAExperten,

It appears that there may be an issue with the cache. I went ahead and purged all the cache from the cache plugin, and then checked the site, and it is working fine on my end. I suggest clearing your browser cache and rechecking it.

Thanks

[DieSEAExperten]

Thanks, but your video in secure note shows sections with missing backgrounds all over the place? It is showing a very broken site.
I’m browsing and testing in inkognito sessions all the time to prevent browser cache.

[tristup]

Hi Daniel,

It seems to be a caching issue. If the changes are not visible when you’re logged out, there may be some server-level cache that needs to be cleared. I recommend contacting your hosting service provider to have this checked.

Additionally, I found that when adding a cache buster to the URL (e.g., ?anything), the backgrounds load correctly. I’ve included the updated URL in the secure note for your reference.

Thanks

[DieSEAExperten]

Thank you for your effort, but I feel it was in vain because I wrote in the initial post what was causing the problem: Pro version 6.7.0 and higher, and WP Rocket with the “remove unused CSS” option enabled. This means that if I disable this option, all backgrounds load correctly. Contacting the hoster isn’t the right approach; downgrading your theme or disabling the important option in WP Rocket will solve the problem. I was hoping you could give me some insight into what you have changed starting with version 6.7.0, because that was the crux of the matter here. I will ask WP Rocket about this but I am afraid staying on 6.6.10 for some time and maybe switching to another theme will be the only way.

[tristup]

Hi Daniel,

I appreciate you confirming the root cause. Based on your feedback, I retested and found that when using a cache buster (e.g., adding ?v=123 to the URL), backgrounds load correctly even with Pro 6.7.0+ and the “Remove Unused CSS” option enabled. This suggests that the styles are present but potentially being excluded or deferred incorrectly by WP Rocket’s CSS optimization.

Regarding changes in 6.7.0 that may impact this behavior, I’ll follow up with our development team to identify any relevant updates related to how background styles are applied or rendered. If we find something that could help WP Rocket better recognize and retain those styles, I’ll share it here.

Thanks

[charlie]

Let us know what Rocket says. If “remove unused CSS” is removing critical CSS then I’d say it’s not working properly, right? Most likely they’ll send you a filter to disable it for our CSS. It’s probably not the end of the world turning that option off, it’s probably not removing that much CSS in general. Originally we were adding a style attribute for background images and color, but to support breakpoint values for each background type we moved to CSS. It also cleans up the HTML output too.