@Gameman @george1421 The wording (“bug”) kept me from looking at this for a while now. Found a bit of time to look into this and I think it’s not a bug really. When editing an image definition there is no drop down for “Storage Group” but a whole new settings tab for this (right of “General”). Here you all should be able to assign images to different storage groups as you wish.
Though I have to admit that it might be a bit of a challenge to find this. Not sure why it was designed like this in 1.5.x.