I discovered that when I placed some upgrade orders (regular granite floor tiles to insulated ceramic) and then canceled the order once it filled the materials were were eaten by the (game? dupe? Tile?) and not returned when canceled whether or not the order has begun to be worked.
edit: determined that the materials are not lost/eaten. they are invisible in the interface until reload. the dupes still register the mateirals and freely take it to be used despite it being invisible.
Steps to Reproduce
start a new game, with sandbox mode. arrange for there to be igneous rock to mine and mine it. in priorities set supply to highest then order the dupes to replace the row of tiles under the printing pod with insulated tiles.. after they have filled all the orders, cancel them and watch all the material vanish into.. ??
This issue has not been confirmed by a developer yet.