Undo messed up my group of objects

I had a group (Background) of subgroups (bushes, trees, fence, etc.) of objects on a layer.

I cut one of the subgroups to paste it to another layer. It didn't do what I wanted, so I clicked Undo Paste and Undo Cut. But on the original layer, it didn't put everything back. Not only did it put the subgroup of objects OUTSIDE the original group, it took all the objects out of its own subgroup and listed them individually.

(Side complaint on the limited number of Undo clicks in Storyline: I tried some other stuff then realized that's not what I wanted and clicked Undo as many times as possible and still couldn't get back to the original group of groups - which had triggers and motion paths - so I now I have to start over! >.<)

I don't know if this is a glitch or a known system issue, but I thought I would share that Undo doesn't always go back to what you originally had. :(