Best guess at reproducing this:
1. Iron ore found
2. Busy build queue blocked by something big that cannot be built yet (needs more tools and wood)
3. Iron mine added to queue (waiting..)
4. Wells and Fields added to queue (pushed to top and executed)
5. Iron mine removed from queue (build had never started)
6. BUG Found: Graphic appears and destroys the Iron mine that had not been built, and then the Iron deposit is also destroyed