Well it is longrunning, common problem when buying, selling and upgrading many units. I have had it happen all sorts of ways from finishing an army leveled to 65, then after reload there may be three units level six. To selling units where they do not actually disappear and selling them 100x over just to see how much resources i can collect before game catches up. Fixxses it self or goes server disconnect and force a reload. Best practice when building a new base or selling one off. Before you start reload. Once finished reload again to make sure its right. Because it is deceptive errors. I have thought wow fun error and messed around and sold alot of stuff i did not intend to. After a while thugh you do start to recognize the early warning signs of a server "hiccup"