Game mode: [Online | PVP ]
Problem: This is the second time I crafted a vault to see it disappear, last time in front of my eyes, only remaining a bag with what was it it.
Region: South America. Server PVP 1996
Well, just what I mentioned, the first vault I built disappeared with no reason at all, the second one literally disappeared in front of my eyes as I was approaching it, it turned into a bag with everything that was in it. Happened in PVP Server 1996, Latin America.
Steps on how to reproduce issue:
- Build a vault
- Place it anywhere (I did it in the region below the mountains)
- Vault disappears without being attacked.
Vaults have a very low decay timer. Check with repair hammer 
This last vault was crafted a few hours before it disappeared just before I could approach it, was even able to see it from the distance.
I also can report two disappeared vaults on the official server 1033.
At the first one, I cleared some rubble and placed the vault. A few hours later it was gone.
The second one was placed without clearing any rubble. It disappeared with all the stuff inside after two days.
Maybe it dropped a loot bag.
My guess is that it disappeared after a server restart.
Both vaults were placed under water.
Yeah, Vaults have 1.5h (+24h) decay if placed by itself I believe. Its normal for you to see it just as it loads in and decays away, if you are the first one to load it in after it decayed away.