Cause

You have applied the shield of a cable displayed as distributed in the schematic more than once. Or you have placed the shield of a cable twice without shields that can be placed on both sides being permitted.

Solution

1. Double-click the cable definition line(s) and activate the Allow shields connected on both sides check box in the Properties <...> dialog. Or alternatively change the name at one of the shields at one of cables displayed as distributed or placed on both sides.
2. Update the connections.
3. If required, start a new check run.