I did a little experimentation and figured out why it suddenly started working for me. The answer is: it didn't. The selection and use of the hoops works just fine when I first open the app up. However, once I click on the Monitor tab and then back to the Prepare tab, that's when it stops working. As I workaround (at least for me) you only need to close and re-open the app making sure not to click on Monitor tab until you no longer need to interact with the translation tools.