As state in the topic
I wasn’t having this issue for the last couple months, but just start to have this problem from couple days ago. I think there was an update for coursera webpage, and I cannot submit my quiz and assignment anymore after that.
Hello @pbpwang,
This post is the solution from a learner who experienced apparently the same problem. According to the post, it was due to missing names in their Coursera profile, which appears the same as shown in this part of your screenshot:

I suggest you to check the name in your Coursera profile.
Cheers,
Raymond
Thanks for letting us know what happened!
Cheers,
Raymond