I designed a PCB a few months ago, and after prototyping we have found a short circuit between a via and an internal power track. For an unknown reason I didn't see this problem earlier and when I reopen the PCB layout file I still don't see any mark from Altium indicating this short circuit. What I have done to see this short is to un-tent the via which was tented.
Does anybody know why Altium didn't indicate this short circuit to me before? Normally I run the design rule check so I am a bit amazed that I didn't catch this one. I attached two screenshots of the issue I had. One screenshot is taken immediately after reopening the layout file, and the other shows the violation I got after un-tenting the via. I didn't touch any design rules between the two pictures (I just un-tented the via)