Remember, some time ago Google has removed the order amount in USD from their Merchant Console? Ever since, I've used the earnings report at the end of each month to capture that data item.
Two months in, starting with the March 2017 earnings report, that's not an option, either. The order amount is there, so is the transaction fee, but the order ID isn't.
At least the support representative seemed to agree that it was a bug.
UPDATE: they've fixed it without any announcements.