I know this doesn't really address the problem, but I found a workaround for this file, though it only works if you are using Acrobat Professional Extended.
In Acrobat Professional Extended, if I right click on the active 3D annotation in APEX and select "Edit in 3D Reviewer..." from the context menu, the model is displayed in the 3D Reviewer. I can then go to File > Export... and export a PDF that then shows a model. That PDF opened in the Reader wihtout issue. I don't know if there is anything missing from the model at this point, but it appears to work. Workarounds aren't great, but they're better than no workaround.
Hope this helps.