Non existant build jobs that can't be cancelled

I don't know when exactly this happened but I had told my dupes to build a wire, but when I checked on the build job again, it didn't exist anymore even though it was still visible. It even overlapped with existing wire. Relogging removed it. I don't know what could've caused it, another application opened a window while I was playing and it might've been while I was in the middle of placing the wire, but I don't remember when it happened.