"We upgraded from QB Pro 6.0 to QB Premier 2016 with a pretty smooth transfer of the company file."
Honestly, taking it through interim steps might not have prevented this. Your old data was from Before this was a relational database and just Tables. If you could have taken this file through QB 2007 or 2008, at least, then, perhaps 2012, and then 2016, and rebuilding in between, the Memorized Reports still might break.
You are lucky everything else seems to be working. This is like Dog Years. A computer lifecycle is 18 months, and QB is 3-years. You just came back from Time Travel!