Using creative mode I have created a "hidden" workshop/storage area at y coordinates 1. It is only at this location I have encountered the glitch which is intermittent. The glitch happens most often when opening a shulker box or transferring items to or from a shulker box that has just been opened, it has happened a couple of times with barrels, but with barrels it has been less fequent. The glitch may occur in either creative or survival mode. I am usually in a peaceful setting. When the glitch occurs I fall though the bedrock below as if it is not there and fall into the void below the map.