Student Answer is correct, but he can't move on

On step 4 of the Single-Page website, my student has entered the correct answer, but is unable to move on. Attached is a screenshot of the student’s answer, which matches the model answer. One difference that I see is that the student’s answer isn’t in a white textbox as it normally would be. I’ve never had this happen before and I’m not sure what to tell him.

Screenshot 2020-04-22 at 1.28.02 PM

Hi Margaret,

Thank you for reaching out! We’re sorry your student experienced this issue. Can you advise the student to reset the current step? Here’s a step-by-step instruction on how to do it:

Please let me know if this will be resolved. If not, we’ll try something else.