0.5.11a win10 64
If you venture outside with 3 supplies and consume them through the rest option without obtaining any extra supplies, when you get back to the mansion it will say you have "0" supplies on your backpack and you can press the "move" button to send it to the inventory increasing your inventory amount of supplies by 1.
Edit: another bug. if you close your "Storage and gear" menu with the backpack selected when you open it back it will show up your inventory but the icon that's displayed is the backpack one. This bug also happens on the market though it may not replicate through these exact steps.