This is easily reproduced on https://muppets-qa.jira-dev.com/wiki

1. Click add page
2. Click insert macro
3. Wait... very patiently..... you'll eventually see the macro browser load (would be nice if you got a spinner)
4. Try and insert a macro
It ends up inserting something in the editor, but doesn't actually close the macro browser.... you can't ever close it BOo