I have exactly the same problem. I've been successfully converting currencies for the past year, now I get: "Some of the information required is missing or incomplete. Please check your entries and try again." I discovered that in my settings...account settings....money and cards, look for currency management, only "GBP" was listed. I added USD here and then the conversion worked. Not sure why USD wasn't in the list as I do have a USD account and it's always worked before.
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