Syntax error issue on not network equipment chain [on nwdiag]

Question

Hello PlantUML team,

There is an issue (Syntax error? on 1.2021.0) on not network equipment chain (USB, ...) on nwdiag:

@startuml
nwdiag {
  a -- b [shape = cloud, address="USB"];
}
@enduml

[See on Plantuml server]

Here is the expected result with the same code on nwdiag website:

Thanks for the support,
Regards,
Th.