I've noticed recently that building orders just disappear from my building queue. Usually it's the third slot that clears itself for no reason - when I have three buildings queued up, the third one gets erased from the queue, just like that. It's particularly annoying while rebuilding wells/wheat fields; the task is menial enough with the default three slots, but try doing it with only two! If I am so lucky... because today, when I had a well already being built and a coal mine in the second slot, the coal mine order also cancelled itself, and I had to re-do it. It doesn't correlate with lack of resources - I never start building things without making sure I have enough resources to do so. I don't think I can blame my Internet connection since it's rather stable most of the time, and besides, the orders do get placed in the queue, they just disappear a few seconds later. I can't exactly take reliable screenshots of something like that, but maybe someone else has had this problem and knows how to solve it? It's becoming really annoying.