Hello,
This may happen if the newly created user account is created by the same setup package as the one configuring the service installation.
The only workaround will be to create another setup package which will create the user account and add this setup package as a pre-install prerequisite to the current package. Just follow the steps from "Install a service for a user created by your installation package" of the
"How to install a service for a custom user" article.
All the best,
Daniel