I'm running 3.9.3 freshly upgraded from 3.9.1 the new encrypt button is available which is great. However if you click the edit button and edit a value and dont toggle the Encrypt / Do Not Encrypt options (even though Do Not Encrypt is already selected) and hit save, it encrypts the value and hides it. Luckily you can hit back a couple of times and the value is still in the browser.
If you simply toggle from "Do Not Encrypt" to "Encrypt" and back to "Do Not" it will not encrypt the value. Clicking "Do Not Encrypt" when it's already selected does nothing and the value will end up encrypted. If this value of "Do Not Encrypt" is already auto-populated based on the fact that the value is not encrypted it should pass through and keep the value unencrypted.
This is a major administrative bug and I will be reverting to 3.9.1