After Submitting the Build it still says Prepare for Submission? Why is that?
Prepare for Submission
For how long have you been waiting ? It can take a long time (several days), even if it is usually fast. https://developer.apple.com/forums/thread/29037
What type of app is it ? Medical apps, Gambling app for instance can take longer.
A possible cause: check all your contracts and all metadata of submission.
See this old thread: https://developer.apple.com/forums/thread/77141