Subscription & nested fields

With a subscription:

https://jabber.happy-dev.fr/conference.test1.startinblox.com/happydev_muc_admin
https://api.test1.startinblox.com/circles/

When I post a new member to https://api.test1.startinblox.com/circles/1/members/, I have no notification sent to https://jabber.happy-dev.fr/conference.test1.startinblox.com/happydev_muc_admin.