When using the Convert to Linestring TML, I had a lot of extra linework all of a sudden appear that was not there before. Gary informed me that polylines can be marked visible or invisible on an individual level.
Maybe there should be something in the project cleanup tool to check for these? enhancement request Maybe relayer these so they do not flood good data. In the project I was working with, it looked like the hidden data was associated to a block that came through.