It happened this early morning, about an hour after maintenance. I had found the Plate Carrier and Pouches beforehand. Then, I found the Gun Holster at NWAF tents and attached it immediately. My full inventory vanished as soon as I attached the Gun Holster to the already built Carrier and Pouches.
I should have thought more about what I was doing before attaching the holster, but I was excited to have found the full set.