I'm just trying to store weapons and armor. For example, a few days ago a blue engram decoded into legendary titan armor which I wanted to put into the vault in the event I decided to create a titan. It took until yesterday for me to be able to do that, and the window in which I was able to store/retrieve items was incredibly short. Tried to move a weapon into the vault today and was unsuccessful. I have plenty of slots available, but when I try to interact with an item the bounding box blinks red. I'm not sure if this means anything, but the characters in question were all created on the PS3. I only recently upgraded to the PS4.