The default behavior of links attached to groups is that they connect to the gravity decoration. If a group does not have a label, an icon, a secondary state or any other gravity decoration, the link connects to the base of the group. If the group has a label, the link connects to the label so that you can only edit the link ports around the label. The same is true for other decorations as well as for the plinth.

You can change this behavior through the property linksConnectToBase to make sure that the links always connect to the base: