BUG: Cannot transfer items from inventory to equipped fanny packs.
Workaround: drop or transfer items outside character and then transfer back into selected container>fannypack.
Not sure if I can drag and drop items in fanny pack from inventory with a mouse, but with a controller using item menu's to transfer > into inventory or backpack - fannypack option does not show up even though it is equipped and has space for it.
Maybe the game doesn't recognise this extra storage yet IDK..