I have run into a special problem in my last design and created a test-project to confirm it.
As you can see the lower +3V3 power symbol is not connected to the line connecting to pin 2 of the connector. This leads to a unconnected pin in the layout. Neither the ERC in Eeschema (where I would expect an error message) nor the DRC of Pcbnew will raise an error here.
For not-power symbols a unconnected pin like this will show up as error in the ERC. Is there a reason why the check is not also done for power symbols?
With labels you can also have this problem.
test.zip (16.8 KB)