This doesn't look like one of your public projects so I'm guessing... Does the pin with the netname of U1_19 show up as being not connected in the Nets section of the Design Manager? What does Nets in the DRC say about the track that has been shifted?

Andy, If I looked at the nets, all were fine and connected. Even if I deliberately pull this trace to touch the pad, no error comes up in the DRC and it shows no error in the nets.

Andy, I even tried it on other pads with other nets, and the DRC error does not come up. I pull it so that it touch another pad, but I make sure the net is connected. My Design Rule setting look as follows: 

hi， Issue confirmed, when the pad does't have the net, the DRC won't detect this error. waiting for fixing. thanks

Tested this all over my PCB layout. DRC error does not detect a clash with a pad. The DRC still works if one cross one track with another.

@Tutorials , Thanks for the reply. The PCB I ordered that arrived on Monday had this problem and it shortened out an unintended Arduino pin with 5V because of it. Took some time to get the fault. I could rectify this, but I had to scratch off the track with a blade and solder in a wire. Obviously I will have to remake the board. Koos