How to show custom shape in thie Viewer?

I succeeded in creating a custom element in the modeler.
But that does not appear in the viewer.
It looks like the original shape.
type: bpmn:ServiceTask

how to show custom element shape in viewer??

modeler:
25

viewer:
34

Can you provide more context? What example project is yours based on? What modifications did you make? Can you share any code?

Have you had a look at the custom elements example.