I just contacted Google Support about this and they said the following:
Currently there is an internal bug which is the cause for this issue. I'm very sorry for the inconvenience, however there currently isn't any update on the matter as of yet.
They said they would email me with an update once there is one and I will post it here when I receive the email.
I would suggest not generating a new certificate if you've already published apps with the current one you are attempting to use.
저도 오늘 업로드 하는데 같은 현상이 일어나네요..ㅠ
문제가 뭐지...해결은 어떻게 하는지..