[BETA] Cannot go to next step - Basic Node and Express Challenges

The title says it all. Here is the URL:

I am running Safari 10.1 on MacBook Pro, OSX 10.12.4.

I’m sorry but your title really doesn’t “say it all”. When can you not go to the next step?
On 1/2?

On 2/2?

On the following challenge? (If so, what was your input? What was your output?)

What happens to prevent your from going to the next step?

Well, it was from (1/2) to (2/2), but now it seems to work. It definitely did not work about an hour or so ago. That is - I would click the “next step” button but nothing would happen.

Thanks for the response. I had closed the browser and re-opened it several times, so I have no explanation.