I wonder was the original batch request created some time ago? It could be that the actual parameters used by the program have been extended since the original, repeating batch request was created, and some of these may not be updatable by users. It might be worth trying to create a new batch request for the same domain, and see if that works. If it does, then you could delete the original batch request and replace it with a new one.
I am sorry that did not work. I think then that you will need to contact Support and they will probably need to to turn some logging on so that they can determine what is happening in this case. It is indeed rather strange.