Acoustic Panels shift during group and rotate

I am working with a dealer who sent me a imported Sketchup design with a problem that he had installing acoustic panels in the model (Opening falls outside the surface boundaries). I managed to get the final panels installed and then decided to center his model and rotate it so it would be easier to determine speaker coordinates after he had finished his design.
The first move (Phase 2 Model) went fine and everything stayed in place. When I selected all the surfaces and grouped them, things also went well. As soon as I started to rotate the model to the right, Several of the panels “popped” out of the model. I finished rotating the model and then had to close it to move to another project. When I went back to the model and reopened it, I got many of the “Opening falls outside the surface boundaries” messages and when the model finally opened, all of the panels had been displaced in the model and most were floating outside the room (Phases 3 grouped and rotated). I went back and redid the Phase 2 model steps (grouped, rotated and then ungrouped) and all the panels jumped out of the model again.
See attached models and jpgs for examples.