I can't reproduce this one by logging out/back in so it might have just been a one-time fluke from when the inventory display transitioned. I also neglected to take a screenshot when it happened :(

When I logged in, my new inventory display showed me as having zero swords. Now, I knew off the top of my head that I had a proto sword, but it was equipped to my person. I opened and closed my other inventory dropdowns (armor, materials, etc) and even my equipped items were visible.

When I unequipped my proto sword, it showed up properly as me having one sword and that category could be opened and closed. I re-equipped the sword and the display changed accordingly, like it's supposed to. It's all working fine now and I've tried logging out and back in to reproduce it with no success