Unfortunately, after mailing the new piece off to my customer and tracking it through delivery, there was radio silence. I worried that she didn't like the piece but also considered that she may have just been waiting to open it on a specific date (an upcoming birthday, for instance) so I made a mental note to send her an email in a week or two to check in. Before I could, she emailed me, and it transpired that the package was, in fact, not delivered (or possibly, not delivered properly and stolen off communal property).
Queue multiple weeks of back-and-forth with UPS, but finally the insurance paid out such that I had been paid to make the commission and my client received a refund on never having received the commission, so we were both made mostly whole again. Even though it's possible it's now lurking in a box in a UPS subbasement or was pawned for the value of the frame, I like to imagine the painting is hanging in a place of pride over a drug lord's couch somewhere. Since I do have the digital image, though, I can at least run off reproductions, so it's not completely lost to the world.