Class and Thumbnail Class Not Working

[catlist id=4 orderby=date numberposts=0 thumbnail=yes thumbnail_size=normal_thumbnail thumbnail_class="tbr_cat_archive_img" no_post_titles=yes class="tbr_cat_archive_ul"]

Above is the shortcode I’m using to display all posts from category “To Be Read” on a page. I have the CSS set (in my theme’s customizer) as follows. The goal is to display ONLY the featured image from each post in a responsive grid pattern with no li dot. It was working perfectly, I walked away for a bit to fold some laundry, and when I came back it no longer displays correctly:

.tbr_cat_archive_img {
  width: auto;
  height: 300px;
}

.tbr_cat_archive_ul {
    margin: 0 auto;
    text-align: center;
}

.tbr_cat_archive_ul li {
    display: inline-block;
    vertical-align: top;
}

No new plugins nor changes between the time it worked and didn’t. I added one post, but have since deleted it in case that was the issue somehow. I’ve messed around with the thumbnail size (“normal_thumbnail” is a custom size I added to my child theme’s functions.php) and changed it to a different size, and that did work, but it seems like nothing I do with the “class” and “thumbnail_class” parameters affects output all of a sudden.

Any ideas?

The page I need help with: [log in to see the link]