Hey @Eduardo-Casarero

youre JSon is correct but if you get categories =[] then it seems like a bug.
There is actually a open bug with these categories:

"C__CATS__PERSON_GROUP_MASTER", "C__CATS__PERSON_CONTACT_ASSIGNMENT", "C__CATS__PERSON_GROUP_MEMBERS", "C__CATS__ORGANIZATION_PERSONS", "C__CATS__PERSON_ASSIGNED_GROUPS"

So you need to use the category.read method like @fa__ described.