You may be receiving 403 errors on one or several child Sophos Central Inspectors due to the child tenant being in an “unmanaged” state. The API will return a 403 when attempting to hit any endpoint for this child from the parent tenant.
The child tenant will either need to be managed or have its own parent setup.
More information about the Sophos Central Inspector can be found here: https://docs.liongard.com/docs/sophos-central-inspector