I've been making a bunch of paint cans at a time, but when I go back to my factory to check progress they're gone - around 10 have disappeared on me today :( I haven't been able to catch it in a pic, at first I was questioning my sanity, lol.
Stuff like this can happen if you close the game (or it crashes) too soon after you do something. It needs to synchronize to the servers. Best way to avoid this is to tap on the Contest tower just before logging off. That forces a synch and should help avoid this scenario.
Try checking your shop for building supplies to see if they are hanging out there, Last time I checked, I was only able to produce metal, wood, chemicals, minerals, etc in factories.
