Limit to content in a CMS collection?

I’m uploading some design case studies that are rather image/content heavy, and I’m running into an issue where one particular collection item isn’t allowing any further images. There’s 5 images successfully added, but when I go to add more, the file uploads (while showing a thumbnail), shows a green check mark, and then the thumbnail disappears. The image is viewable if you launch it in its own window, but doesn’t display on the site.

At the point of this failure, there’s just under 5MB of images in the collection– is that another arbitrary limit set or is there some other explanation?

Any help is greatly appreciated. Thanks.