When Pips critters mess with items contained in storage bins, the item that get dropped occasionally freezes mid-air in front of the storage bin.
There's no way to recover these bugged items, dupes won't interact with them and if one tries to deconstruct the storage bin, the items just disappear.
Several items can become frozen after a while and reloading the base makes the items disappear.
Steps to Reproduce
Store items inside a storage bin and make sure there are Pips around it. Eventually they will mess with the items contained. Wait until one of the items get frozen mid-air in front of the storage bin.
This issue has been fixed in either a future version or updated in a previous version.