First, these had been working. Quite literally, they were working yesterday.
Today, if they finish the code and it is error-free, the white confirmation message displays for significantly less than a second. Then it is replaced by the word "completed" in red. Then nothing happens.
The word "completed" replaces the normal end of compile text extremely quickly, so I can not verify that there is no message in that, but it doesn't look like there is anything than what I should expect to see.
I have exactly the same problem. So far everything worked fine, and today when verifying the sketch in the console the word “completed” appears in red and at the same time the message “Error Verifying...”. Even with the default bare sketch and after removing and adding the device again.