Buildings completing instantly.

I built three outhouses, and once the finished, I started recycling all my junk, getting the materials to upgrade them... ...Two of them finished suddenly, skipping the twelve hours in an instant. This has happened with many buildings, but I'm not entirely sure how to reproduce the bug. I suspect this happens while I'm building and upgrading multiple of the same building. Does anyone else know what causes this? I suppose a developer can audit my game. I read that all the timings are server side to stop cheating through the client, so it's probably nothing to do on my end.