Controller rename from the Actions tab requires the mouse to stay in the text box, different from other text boxes...
When attempting to rename a controller from the controllers section of the Action Groups editor, text entry will stop if the mouse moves outside the text entry box and it is not obvious what is happening since no other text entry boxes I can recall act like that. Also, it isn't that obvious that the name can be changed from there since the edit name icon only appears after clicking on the name.
1) Place a KAL-1000 Controller
2) Click Actions at the top of the screen
3) Click on the controller under Controllers
4) Click on the top box above where fields are added, current name KAL-1000 Controller
5) Click the edit icon, see that the box is now text entry
6) Move the mouse slightly and be very confused why the name you type is not entered