That seemed to have fixed the problem ^^
Can you add the Link To "Custom URL" from Image Details > DISPLAY SETTINGS > "Custom URL" to the gallery?
I made a plugin to do this but your programming is probably a million times better than mine.
Also if "auto" is added to the 1 to 9 image selection part of the gallery like in the plugin that was made then this core component will work just the way any other gallery usually works. Which is a great thing. If standard images can link to "Custom URLs" I just imagine gallery images would work exactly the same way. I was always confused when I started using WordPress, wondering why I could only link single images to custom URLs. I was trying to use the gallery as navigation because it was so easy to set up and looked really good having images instead of a text based menu.
The code in the template area to show the thumbnails has an auto column width in a way. Thumbnail sizes are set and the images tile perfectly across big screens which is very nice.
You can see what I did with the gallery here:
It is a standard gallery with Custom URL built in.
I'm rebuilding my whole site from the ground up in this newer version of WordPress to get rid of lots of bugs and hopefully can delete 40 or so plugins from my last site. ^^