What does SortIsOverridden do?

We are trying to update an Organization Sort value via the Party endpoint to no avail.

For example: PUT /api/Party/28911

{
    "$type": "Asi.Soa.Membership.DataContracts.OrganizationData, Asi.Contracts",
    "OrganizationName": "Lowe LLC",
    "Name": "Lowe LLC",
    "SortIsOverridden": true,
    "Sort": "lowe llc Sorted",
    "UpdateInformation": {
        "$type": "Asi.Soa.Core.DataContracts.EntityUpdateInformationData, Asi.Contracts"
    },
    "PartyId": "28911"
}

While the response comes back with the right Sort value as requested:

    "OrganizationName": "Lowe LLC",
    "Name": "Lowe LLC",
    "SortIsOverridden": true,
    "Sort": "lowe llc Sorted",

It does not stick.

How can we change a company sort value?