I noticed that when I'm in the shop. the woodsman's Axes in my invantory never want to stack on top of each other. Seems like a bug to me.
If both items don't fit one the same line when stacked, that's what happens. Try sorting weapons only - and I believe it will stack.
That it did, but still, I should be able to see how many of each item I have at *ALL* times, not just because there is enough space.