Hello Overseer and welcome to the forum.
Maybe the first thing is to consider what, appart form the layout, might have changed in the new report.
Then perhaps quickly try creating a very basic new model for the new report to see if that works or fails. If it works perhaps check the Input Options for both models to see if there are any differences.
Next steps in the investigation may appear depending on the results of those quick checks so do let us know how it goes.