Good to know that I'm not the only one! In my case, I found that it only happens when I try to edit the App Review information.

This is disappointing!. It's been several days and apple is not able to give an answer ...

Well ... In my case I did all the steps that Dan T. did and now it's saving! Thanks a lot! You solved the problem before apple. They would have to pay you for it! Haha! Sadly, I can't mark your answer as the solution because apple does not allow me to change the check mark. Thank you so much !.