Part way through building a catapult I completed the physics technology. I would have thought that my partly built catapult would either:- a) Continue and complete as normal b) Continue to build as a trebuchet (the catapult upgrade, and just take a bit longer due to the additional cost). What seems to happen is that I lose all production and have to start again. This just make planning builds complicated, having to check what will complete first (assuming I actually remember to check). Is this a bug or just a bad feature? patch level 188.8.131.52 regards.