As I was PVPing in Cherno last night on an open Hive server with a friend, at the end of combat and before we moved off, I realized that my VSS had despawned from my character. I hadn't used it in the firefight, or actioned any items other than the Steyr Aug I was shooting so I don't believe I could have accidently dropped it.

I didn't log in or out recently - had been solidly playing for a good hour at this point with no connection issues or rubber banding/desyncing.

Upon researching it a little online, I have found a video where the same thing has happened to at least one other player......

https://www.youtube.com/watch?v=WJQiaHLN_cc
(27mins in to vid)