I've had this issue a few times, still I don't know if it's a bug or it's there so there's less lag, but either way, please fix it because it's REALLY annoying. First, I was a Venture scout going to a Crafty Mike mission and destroyed a pretty big tech (I don't how, but I did it) but I don't usually have my SCU on my scout so I went back to base to grab it (only took about 2 minutes) but when I came back, all the blocks were gone. Then, on a different save, I was a pretty big tech though I didn't have the SCU yet, I got destroyed but the SCU mission was only a few hundred meters away so I decided to go get the SCU and then when I came back to where I got destroyed, all my blocks were gone again (SCU only took like 5 or so minutes). Reply if you're experiencing this bug as well, or if it's an optimization feature. Again, either way, please fix/change.