I don't see a bug here? This seems to be working as expected. Have I missed something?

Experience in Safari:

1. Open VisualEditor and Insert > Media.

2. Pick and image and add a caption.

3. Select a word and press Command-K to make an internal link.

4. Notice that you get no search results to help you find the correct page for your link.

5. Click inside the box. Now you have search results.

Experience in Firefox:

1. Open VisualEditor and Insert > Media.

2. Pick and image and add a caption.

3. Select a word and press Command-K to make an internal link.

4. Notice that you are immediately given a long list of search results, even if you don't want them.

Since they don't behave the same, then one of these two browsers isn't working as designed.

I think it is the firefox which is different from Chrome and Safari, not sure which one is correct though!And not just for a link inside image, for a link in CE too,in Chrome and Safari, you will not get any list of link target suggestions unless you click inside the box.