RoboHelp 2019 Classic randomly inserts images/text into chapters

I recently built OnLine Help using RoboHelp 2019 Classic for ResponsiveHTML5 output. It all seemed to work fine EXCEPT in two cases, RoboHelp inserted content from one chapter into two other chapters where it did not belong. The FrameMaker files were perfectly clean, as was the PDF that I'd generated through FrameMaker. I was able to work-around the problem by manually editing the files in RoboHelp, but the next time I update the Help from FrameMaker, it's going to do it again. Has anyone seen anything like this and is there a real fix? Thank you.