Nice. Even though in my case I had no sandstone either. But now I know it’s a bit extreme to start out like that.
Details on the backpack bug, if it’s still an issue: I could open it, sort it, add thing to it, but if I hovered over anything inside I got “An error has occurred.” message, and no info box was shown about the item. I also could not remove items (by dragging, r-clicking or choosing remove one/all).
It is surely not connected to decay cause I had only minerals and cobble flooring in it. Also just as a test I made a bag, and it had the same bug.
Then I simply reloaded the game and everything worked fine again. Later could not reproduce it.