Because the prosecution improperly failed to disclose certain items.
In the indictment, it just said that he was guilty of "financial facilitation" of $200,000, but it didn't say which transactions they were alleging as being criminal. A few days before the trial, the state handed over a flash drive with hundreds of thousands of entries, and said, "This is our evidence". It was only DURING the first trial when they learned which entries were the alleged criminal ones. And, when the prosecution showed it, they showed it on a spreadsheet which DID NOT contain the name of the person who made the transaction. (For other entries, they DID show the names.) That being the case, during the first trial, the defense assumed that there was no name attached to it, so they couldn't research it further.
It is also important to remember that there were alleged 5 counts, not just this count. And at that time, a defense on the other counts would've automatically meant a vindication on this count, as it was predicated on the other counts. It was only after the defense rested, when the judge changed the rules to make this count independent, that this entry suddenly became so pertinent.