Dear Ankur,
Yes, we also had the similar issue. If the settlement currency is different from the billed currency, system gives the error and file upload get failed. This happened for both the file format i.e GL1025 & KR1025. This is the standard behavior of the system.
The solution is only to ask the AMEX team to provide the file with the correct currency. We had a call with the AMEX team and were able to permanently resolve this issue by ensuring the correct currency in the file.
Regards,
SUmti Bhadani