Looks like we can't reproduce the issue or there's a problem in the test case provided.
When we move any object on z on Sencha Animator interface, it doesnt represent the real perspective, just when we export. It should get smaller or bigger depending on the position z value.
Per example I had an object as background and another object rotating 360 in y.
On sencha animator interface everything looked fine, but when I exported they were intercepting each other. So I moved the background on z to avoid the interception, but visually nothing changed.
It should get smaller.
Thanks for the feedback! The CSS3 3D support within Sencha Animator Beta is very experimental, so it might not display correctly. If you want to avoid 3D properties you can avoid Rotate X&Y, Position Z and Scale Z.
Its a good response given by you and such feedbacks always motivate others do best .