Can't "unstick" two shapes

I’ve run into a strange and frustrating problem. In one of my diagrams, I have a vertical dashed line running through the diagram. It crosses over a rectangular shape. Somehow, the two have become stuck together. They’re not grouped nor can I find any other type of connection. Furthermore, while I am able to select one or the other element, if I delete either one, the other element gets deleted as well. I’m trying to disconnect them. Any advice?

When you view the Layers Sidebar with those items selected, what shows there? You might have a subgraph in your document. You also could have one combined shape instead of 3 separate objects. It also could be a placed image, and not really 3 different graphics, but the Layers Sidebar will show you the object hierarchy and type.

If you choose Contact Omni from your help menu, you will see an option to include a document. As long as we can see the items that are sticking together, we should be able to help.