I'm almost sure that this is a bug. What happened was that, while examining my layout for possible mistakes, I found two pads that were connected by a trace but which were both assigned to Net 0 - which is my ground net. Since I always use a groundplane anyway, I decided to delete the trace between these two pads and assign them individually to Net 0. I deleted the trace using the "Unroute Trace" command, which caused the trace to turn into a ratline, but it also changed the Net to 69 I believe it was. So, I then selected "Delete from Net" and then selected "Add to Net" in order to reset the pads to net 0. When I did that, I noticed that all the pads that were previously assigned to Net 0 were now assigned to net 69. So, I began to reset all of the Net 69 pads back to Net 0. This was annoying but it was ok because the layout is not that large in the first place. After I had reset several of the pads back, I clicked on the Net 0 entry in Design Manager located at the right of the layout window. When I did this, I noticed that not all of the Net 0 pads lit up red like they should have. Understand that the layout did also contain other Net 0 pads that had not previously changed to net 69 pads, so I did not need to reset them. So, the result of all this is that, some pads lit up red and some did not, depending on if I had reset them previously or not. So now I have two sets of Net 0 pads - some light up and some do not. Below I have attached two photos. One photo shows the Net written as "Net 0" with a space between the t and the 0. The other photo shows Net0 with no space between the t and the 0. I can't imagine why anybody would need Net 0 and Net0.