Why are the default product groups not automatically being added when using externally synced groups

[Danny]

I'm currently testing out using groups that are synced via a SCIM interface (Okta). I've setup completely separate groups to basically mirror the standard Atlassian groups (i.e. app.jira.user, app.confluence.user)

The default access groups are still the same (i.e. jira-software-users, confluence-users, etc.). 

I have updated the product access so that if a user has app.jira.user they are granted access to Jira.

Atlassian documentation specifically says:

• When a user is granted access to a product, they will be added to the products default access group.

When a user is added (via our external directory) to the app.jira.user group I would expect the user would automatically be added to the default group for Jira -- jira-software-users. This does not appear to be happening though. 

Any ideas?