While playing the game, items that support building with different materials (e.g. ladders, tile) change their default material. Suddenly, I'll be building ladders with obsidian instead of sandstone, and I'll use up all my obsidian unintentionally. I can switch it back by selecting a more plentiful material, but I have to do that for each individual option which is a pain since I'll keep making the mistake (oops, gotta fix tiles too!). The new selection sticks until saving/reloading, at which point it'll be reset again on me to something I don't typically want.
Save/reload a game after mining many different types of materials. Observe that the default material type for some items (e.g. ladders) changes to something different than was selected before.