Replication steps are simple and it has currently been tested on Google Chrome for Mac. @Rho Delta do you use Mac or Windows?
- Go to an editor that is currently blank
- Type any text
- Highlight all of the text (click and drag or Cmd + A or Ctrl + A seem to have the same effect)
- Click the Add Link button in the editor
- Type a link
- Click Insert
- The result is that no link is applied to the text.
As a work around if you end your text with a space and highlight everything except the space, then the link will add properly.
Oddly, if you're editing an existing post (for example) then it works absolutely fine.