When reloading the page / re-opening the building view via menu in the absolute exact millisecond before the drone collects the resource you can see on the newly loaded page the amount of collected res above the resource like it was collected but the resource itself is still there and can be farmed anew or if you reload the page another time then this resource is gone. The collection happens in the first time correctly but the model is not removed.
http://prntscr.com/k21gyy