DjangoViewflow - Not executing the complete flow

I've a workflow consisting of multiple nodes.

@frontend.register
class Flow1(Flow):
    process_class = CreationProcess

    start = (
        flow.StartFunction(this.create)
        .Next(this.credit_line)
    )

    credit_line = (
        flow.Handler(this.cibil)
        .Next(this.seynse_score)
    )

    score = (
        flow.Handler(this.seynse)
        .Next(this.score)
    )

    check_score = (
        flow.If(lambda activation: activation)
        .Then(this.send_task)
        .Else(this.end)
    )

    send_task = (
        flow.Handler(
            this.send
        ).Next(this.end)
    )

    end = flow.End()

I run the flow like this:-

Flow1.start.run()

The problem that I'm facing is that it only runs the start node. The following nodes are not executed. Why?

from DjangoViewflow - Not executing the complete flow