Appstore Connect: getting "Unable to Add(submit) for Review" error probably because of copyright

i am trying to update by build in appstore connect, and every time i try to add for review (or submit for review, in the older way) i get the message "This field is required". the full error message is attached below:

enter image description here

listed below are things i've tried and done

  1. filled everything in "Agreements, Tax, and Banking"
  2. agreed the Paid Apps contract
  3. filled in every fields other than optional areas - including copyright

and actually i am assuming that the copyright part is causing the problem because the "save" button doesn't get activated even though i changed the copyright. to make it short i just cannot save my copyright information.

can anyone help me with the problem? i'm currently getting crazy because of this.

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