Jira aui-select in jira Service Desk Customer Portal

Hi Everyone,
I developed a Jira Plugin that implements a Custom Filed that uses the Jira aui-select element, (asynchronous) version 8.5.0 for the front end rendering. It runs on Jira 8.8.1.
The select aui element works beautifully when I use it in the Jira Software deshboard. On the contrary, when used in the customer portal, it is a plain input field where the user can write anything.
In my atlassian-plugin.xml I have

  <web-resource key="form-plugin-resources" name="form-plugin Web Resources">

What I am doing wrong?