So I've been having this issue for a while now, and i'm not sure how to fix it. It started when I redeemed a rank-up package from New Monarchy while having filled up my weapons inventory on my character. Usually, Items should go to the postmaster if there isn't enough space, but the unknown item i may or may not have received seems to have confused the postmaster (the exclamation mark over its head should probably be turned into a question mark in this case). This hasn't stopped me from getting more items sent to the postmaster after getting this issue, and any item manager I've used tells me the postmaster is empty even though I have this notification. Does anyone else have this problem? Is there a way to fix it?
This is a glitch tied to the Armor of Vows ship. If you equip a different ship it will go away.