I feel you pain, something similar happened to us on official server.
I’m guessing here, but it could be a glitch in the server.
back in december we lost every placeable inside an outpost except for a well and a few ground torches, all buildings were intact and there wasn’t a single sign in event log of decay or any activity within the outpost even though we were there several times each week.
Here’s the full post about it:
Just recently our main base decayed, we were in the base on a friday where I logged out.
I didn’t play during the weekend, but on monday evening after the weekend I logged in and found that the base had decayed, this time there was decay messages from monday morning right after server reset that the base had changed state to decayed.
I know some will think, you weren’t properly refreshing it, and if I hadn’t experienced it myself, I would also be skeptical.
But we decided to move on and leave the server and try on a different less populated server, don’t know what exactly happened and I may never find out.
Something like this seems to be very rare, and I wouldn’t want to be the one trying to figure out and fix it, strange things sometimes happens in computer games without anyone ever finding out why 