When you open your inventory and drag a backpack from it's slot on the character window into its own inventory, the backpack disappears and the inventory for the backpack also disappears.

However, when you add another backpack to your character window (into the backpack slot) and use Alt-I to open the inventory it will also open the disappeared backpack - Rylec right now has 10 backpacks when I use Alt-I (the six from the character window + four I destroyed like described above), and since the backpack itself disappeared I don't see how I can destroy the extra bags properly (in game).

i will take a look at this