Upon loading 1.16.5RC for the first time, ALL blocks and items related to copper, amethyst, calcite, tuff, and bundles, are missing from my existing builds and inventories. They are just 100% GONE. This includes cut copper stairs used in a roof, and the spyglass made from copper and amethyst. Nothing that existed before the 1.17 snapshots appears to be affected; only things that have been related to the Caves & Cliffs update. Using cheats to return items brings back an error line that items are unknown. All of the affected blocks and items have been working perfectly, until this snapshot update. I was not prompted to backup my world before loading, as with all previous snapshot updates, nor was there an option to choose to backup on my own initiative.