The bug happens when Relm misses the target she is supposed to sketch or when there’s a difficult to sketch enemy. The bug has various possible outcomes, among them are dropping multiple items into the inventory (Gem Boxes, for instance), freezing the game or deleting all data.
It’s the easiest to do on enemies who casted Vanish on themselves.
Either way, the original FFVI was chock full of fun glitches. My usernick comes from my favorite bug in FFVI.
This glitch rocked!! I would do my best to draw near a save point and find my way back. If you did this successfully you could restart your game (from your save point) with +99 of some of the best items in the game.