Three days in a row, since I first placed it, every time I log overnight, at my next log in I find that my Colossus has moved off/away from or is completely missing from its pad.
The ground is perfectly level. There are no Thumpers or other heavy machinery nearby with the exception of an array of supply depots, so I’m scratching my head.
I never drive the thing (perhaps it is getting lonely?), but only use it for necessary storage (42 slots!).
Anyone else have this problem?
You don’t have any butterflies do you? They try to take my Roamer on a daily basis. 
All of my vehicles move around like this. When I had a building around them they would get jammed up in ways that I could not drive them out of, once it ended up on top of the building. Just guessing: I think that when the ground goes through the LOD changes, the pads move up and down. In the past the vehicle would land back on the pad as it moved. Before Beyond the roamer would often go into a state where its wheels would be spinning, now that they are larger I think they land on the slope at the edge of the pad and the physics starts the migration. The other thing that happens a lot now is that my nomad will fall through the geometry and end up landing on the underground water plane. (I fell through once and found it down there, but I got reset before I could climb in.) It seems that the vehicles are growing up and starting to move out on their own.
Hah, yeah the LOD change is exactly what I was going to suggest. When I had my base complexity set to High, every time I walked away from my exopads, they would cycle from high to low LOD and all the vehicles would get flung way off. Changing it to Ultra fixed that for me (at least for now).
Beyond’s LOD handling is still pretty screwey. When I load the game at my base, all my crops are rendered at horrible low detail and don’t improve even if I walk right up to them. However, if I approach my base from a distance, they (usually) render at the nice normal detail.
If it’s got to do with LOD-ing it should be fairly easy to observe if you save in a position from which you have a visual on the colossus and then reload.
No butterflies, but…
:looks askance at the large swooping birds:
EDIT: I just deleted the Colossus’ base and put up one of those radar thingies. As I said above I don’t generally use the Colossus for anything but storage. It hasn’t moved since so perhaps there is some thing to what @GullyFourmyle and others suggested here.
I have this problem in my VR save, I’ve even witnessed the thing driving itself down some hills and into the ocean 
It seems to glitch into its spawning port when you load in and the collision makes it bounce into the air, force it into the tunnels below my base or send it rolling down the hills
