I have found the solution, and misrepresented the problem in the original post. When the ScottCare message was generated, a CR and LF followed the message, which was inconsistent with my working thread. I deleted those markups in Notepad++ and tried to rerun the file. The message still did not go through, which was why I posted that the format was the same (as it WAS, but only once I manually edited it). I had disregarded the CR LF as the potential issue because removing them did not allow the message to pass.
But once I dug into it more, I realized I had not put a -nonewline on my puts command when building the file. I did that, reindexed the thread and set up a test patient for next month to generate a text file. It crossed.
The odd thing is that I would have thought that the engine would have returned something even with the CR LF on the final line. On top of that, when I manually edited those out, I’d have thought the message would pass.
It’s funny that explaining the issue is sometimes the best troubleshooting you can do. I spent a while trying to figure this out, but didn’t put everything together until I started bouncing the issue off of people.