Hi Bill and welcome to the forum.
Seems like and odd problem although to be honest I don't recall ever having to work with a report of 20 columns so maybe an undiscovered 'issue' from my personal experience.
If your input file is a set of comma separated values as you posted then my personal initial recommendation, since you have Monarch Pro, would be to consider reading the file as a database (a csv file counts as a database for this purpose) and extract the fields that way.
You may already know this and have a reason for not going that route, in which case let us know. I'll experiment with the MCR to see if I get the same result if you have to look at that option rather than reading as a database.