F5 access , autofill username

We have setup a Network Access via the APM where we have added a extra field on the logon page.

It is used for entering the one-time password from Google Authenticator.

Endusers are using the F5 access app downloaded from the App store to connect to this service.

The problem they are experiencing is that the username which is saved in the app is not autofilled in so they must enter it again.

Is there a way to make the app remember the username when using the app?

It works fine on other Network Access where we havent customized the logon page

Best regards

Daniel