Line routing not consider for group nodes. Please find the below steps to replicate the issue.
1. Set the diagram constraints with LineRouting.
public diagramConstraints: DiagramConstraints = DiagramConstraints.Default | DiagramConstraints.LineRouting;
1. Create 4 nodes:
Node 1 is connected to Node 2
Node 2 is connected to Node 3
Node 3 is connected to Node 1
Node 3 is connected to Node 4
2. Then create a group node with Nodes 1, 2, and 3 as children
3. Trying to move/drag the group node, and group nodes do not move.