When SCIM enabled on an OKTA Workforce Enterprise connection app_metadata is deleted rather than merged after an update

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I have set up an OKTA application and enabled SCIM provisioning to my auth0 tenant. This works as expected. New users are created, existing users are updated and deactivated users are marked as blocked in auth0. However our application adds an application specific field to a user’s app_metadata field on first login. This attribute is deleted each time the user is updated in OKTA and the updates provisioned back to auth0. If I add it to user_metadata it is persisted. There is no name clash with attributes provided by the SCIM mapping. It is not a field that users should update so it should be stored on app_metadata. Please help.