They don’t lose storage groups going from 1.1.2 to 1.3.0 (any rc you want).
They don’t lose storage groups going from and version 1.2.0 and earlier because Storage Groups for snapins didn’t exist at all.
Trunk introduced the idea that snapins work in a similar fashion as images and because of this should be allowed to replicate and move around to different groups and nodes.
So it’s no surprise they don’t have group settings defined. This is because we don’t know (we being the FOG team) how you intend to use your snapins and think it’s safer to allow you to setup how you need it setup.
Please define your relevant storage groups and reupload the files as needed. This should fix the storage group problem for you too.