Hover caption over portfolio with link behind caption

Hi there, 

I'm having problems using the following custom CSS on my website. 
I've used the exact same code in january 2022, without any problems. Doing the same now, with a new website and it's not working. 

Are there problems regarding the new Fluid Engine? 

Or does anyone have a solution? 
Does the custom CSS need a change?

- Cheers :)

______________________

.gallery-caption {
position: absolute;
top: 0;
left: 0;
background: rgba(0,0,0,0.4); /* overlay color */
height: 100%;
max-width: unset;
padding: 0;
opacity: 0;
}
.gallery-caption-wrapper {
display: flex;
align-items: center; /* center vertically */
justify-content: center; /* center horizontally */
}
.gallery-caption-content {
font-size: 1.5rem !important; /* caption font size */
color: white; /*caption font color */
}
.gallery-grid-item {
position: relative;
}
.gallery-grid-item:hover .gallery-caption {
opacity: 1;
}
.gallery-caption-grid-simple {
transition-delay: 0ms;
}
.sqs-portfolio-image-link:after {
content:'';
position: absolute;
width: 100%;
height: 100%;
top: 0;
left: 0;
z-index: 9999; }

I've also tried with this bottom part instead, without any luck.. 

}
.gallery-grid-image-link:after {
content:'';
position: absolute;
width: 100%;
height: 100%;
top: 0;
left: 0;
z-index: 9999;
}

Can you share link to page where you want to apply the code on your new site? We can check easier