Seems like a bug:

The user:

1. Edits a question
2. Then, he decide to close it.
3. Clicks on the Close button.
4. The popup doesn't appear.
5. Refreshes the page.
6. Click on the close button.
7. The popup appears.

After editing in the link appears a hash: #. But I don't think that this is the problem because if I add the hash without editing the close popup appears.

It's minor, but I think that is good to be reported and solved.