Note:
The counterpiece of a male pin is either the female pin with the same DT and the same pin designation or a female pin that is connected with the male pin via direct connection points.
Cause
A plug definition was placed in the schematic for which "Plug definition for female pins" was entered for the function definition. This setting makes the program search for a corresponding item, namely the male pin side. However, this counterpiece is missing in the schematic.
Solution
Add another plug definition to the schematic and enter "Plug definition for male pins" for the function definition. For the plug definition, enter the same DT as you did for the female plug definition.
Refresh the connections and then start a new check run.