Custom Template Issues - Media Library Gallery

I'm working with a custom theme that was developed by a well-known team a few years ago. The client wanted some unique features that were able to be delivered, but I'm having an issue now updating a special gallery setup.

The page template is set up to display rotating images in a 675x455 pixel size, with both the Title and Caption for the image displayed as text in a specific position on the images.

Example here:

The page is set up with JUST a WordPress Gallery in the main content section of the page. The video section and the text in the middle section below the image are Custom Fields.

The issue: When I change the Gallery images, the images on the site are NOT updated.

Note that if I change the Title or Caption for an image, it does update. If I try to delete the image, it does not go away. If I try to add images, I can not do that.

I do not have a caching plugin activated.