Looking at the “Add user to group through User Custom Field” script, there seems to be a bit of an issue. If the “User first logged in” trigger is selected, the “User Custom Field name” input should be set to the name of the User Field, for example “Native Language.” But if the “Recurring” trigger is selected, the “User Custom Field name” input needs to be set based on the User Field’s id. For example “user_field_5”.
Just to note, this is mentioned in the walkthrough:
I’ve mentioned about reworking the script for consistency, though it’s not been prioritised yet. There’s also the public user custom fields and staff user custom fields admin settings that would be nice to bring into line with it as well.
(And there’s also poll groupable user fields too, which uses the ‘friendly name’)