When 'waking' my Mac, the password box auto fills....

.....with a pasword that I can't see (obviously). When I click on -> password is incorrect, and it just 'wiggles'. Then, I try to highlight the incorrect pre-filled password, and enter the correct password, it pre-fills again??

Happens on an intermittent basis, and I can't say for certain it is El Capitan related. What is going on and how can I fix this? 😐