"Transactions can have only one foreign currency at a time". What can we do?

Hi,

I am trying to record a simple transfer (in transactions>bank) between a bank account in EUR and another bank account in IDR. When I try to do so I have this error message preventing me from doing it:

"Transactions can have only one foreign currency at a time."

1. Why?
2. What can I do about it?

My company is in the UK so I have GPB (and USD) activated but I don't think this has anything to do with it?

Let me know if there is a workaround.

Thanks a lot,

Alexis