Hi @pinggi
Are you using the Inprocess version with the v4 host? Azure Functions v4 Host has a bug that causes singleton factory registrations to be resolved by the child scope and not by the root scope as they should be.
We are working on a fix, Adjust DI usage to workaround Host v4 bug by andreasohlund · Pull Request #361 · Particular/NServiceBus.AzureFunctions.InProcess.ServiceBus · GitHub for the host at the moment. It might take a while though until it is ready and fully releasable.
Regards,
Daniel