Support has advised the following behaviour for the auto-subscription (Follow) notifications and requested to post a feature request:
As per current functionality, the auto-subscription(Following) flag will not automatically update for the newly added CSM to the company.
Admins have to manually re-save the Notifications Settings from the Administration tab to update the auto-follow for the newly assigned CSMs
My expectation is that when the CSM field (or another field configured in Administration > Notifications Settings) is updated, the relevant User will be auto-subscribed to notifications for that Company as per their personal notification settings.
It would be great if this functionality was enhanced so that this happens, rather than needing to periodically re-save the admin notification settings.