Hi there, @econnolly.
Let me share additional information about closing out gains from foreign currency exchanges.
Mixing currencies in your journal entries may lead to incorrect open balances or incorrect exchange gains or losses. Since you have a discrepancy in your balances, I suggest following the steps on option 2 and option 3 in this article: Multi-Currency: Journal Entry Error Message. This will help close out gains from foreign currency exchanges.
Come back to this post and let me know how it goes, @econnolly. I'll be around to provide further assistance.
You may also want to learn more about using your own exchange rates in QuickBooks Online. You can check out this article for more details: Enter and use your own exchange rates.
Have a good one.
