If you create multicurrency payables (PM) transactions using eConnect, and you are passing in the distributions manually (by setting CREATEDIST to 0), you may have encountered the same issue I encountered today. When the transaction was created, eConnect also (correctly) added in a ROUND distribution, to account for 0.01 cents worth of FX related rounding on the transaction. Unfortunately, eConnect did not populate the distribution with an account.
See more here:
Populate Rounding Account On Multicurrency Payables Transactions Created Via eConnect