Hello Josh,
Thanks for using GWD.
We are aware of this 3d animation issue when you apply 3d animation with a background. It is more obvious to see the z rendering issue in Safari browser.
To workaround this, I added negative z values for translation for all four background images (frame4bg, frame3bg, frame2bg and frame1bg).
Please take a look at the attached file and play with values for Z translation. To do this, please select the very first keyframe of each layer (frame4bg, frame3bg, frame2bg and frame1bg), then from Properties Panel, change Z(negative px values) for Translation.
In this way, the box flipping animation won't go behind the background images.
Please let me know if you have any question,
Thanks,
Mariko (GWD team)