Unfortunately so far I was not able to reproduce this.
Here are my tests:
-create a new scene with Corona 1.7.4
-place some objects (teapots), convert them to proxies (precisely: created 3 teapots - one editable poly, one editable mesh, one editable patch, duplicated them multiple times as instances and copies, changed their scales, rotation, position)
-created 2 scatters and scattered the proxies on planes
-opened the scene in Corona 3 and 4 RC1
-the scene looks in viewport and renders exactly the same in all versions
We will need either:
-exact steps how to reproduce the issue
or
-a scene where the issue can be reproduced consistently
The uploader is in my signature.
Thanks in advance for any feedback you may have!