Uploading style (SLD) to GeoServer using REST API not working - for empty workspaces

I am trying to upload a layer using the GeoServer (2.28) REST API using the Importer extension in python. I ak not not what I am doing wrong.If I use the PUT method when the sld does not exists in an empty workspace, it will load the layer and sld but will not apply the styling. If I reload a second time using the POST method for the same layer and sld in the same workspace the style is applied correctly. below are the code I am using, but I cannot figure out what I am doing wrong:

1.1 To upload a layer - (workspace is empty):

# Step 1: Create import job
POST /rest/imports
{
    "import": {
        "targetWorkspace": {
            "workspace": {
                "name": "city"
            }
        }
    }
}

# Step 2: Upload file to import task
POST /rest/imports/{import_id}/tasks
Files: towns.shp, towns.shx, towns.dbf (multipart form-data)

# Step 3: Execute import
POST /rest/imports/{import_id}
(no payload)

# Step 4: Execute task
POST /rest/imports/{import_id}/tasks/{task_id}
(no payload)

1.2 The SLD upload handling - (workspace is empty):

# Check if style exists
GET /rest/workspaces/city/styles/towns.json

# Since workspace is empty, style doesn't exist → CREATE NEW
POST /rest/workspaces/city/styles?raw=true&name=towns
Content-Type: application/vnd.ogc.sld+xml
[SLD XML content as raw bytes]

# Assign style to layer
PUT /rest/layers/city:towns
{
    "layer": {
        "defaultStyle": {
            "name": "towns"
        },
        "enabled": true
    }
}

2.1 To upload a layer - (workspace is not empty):

# Step 1: Create import job (SAME as Scenario 1)
POST /rest/imports
{
    "import": {
        "targetWorkspace": {
            "workspace": {
                "name": "city"
            }
        }
    }
}

# Step 2: Upload file to import task (SAME as Scenario 1)
POST /rest/imports/{import_id}/tasks
Files: towns.shp, towns.shx, towns.dbf (multipart form-data)

# Step 3: Execute import (SAME as Scenario 1)
POST /rest/imports/{import_id}
(no payload)

# Step 4: Execute task (SAME as Scenario 1)
POST /rest/imports/{import_id}/tasks/{task_id}
(no payload)

2.2 The SLD upload handling - (workspace is not empty)::

# Check if style exists
GET /rest/workspaces/city/styles/towns.json

# Since workspace already has styles, style likely EXISTS → UPDATE EXISTING
PUT /rest/workspaces/city/styles/towns.sld?raw=true
Content-Type: application/vnd.ogc.sld+xml
[SLD XML content as raw bytes]

# Assign style to layer (SAME as Scenario 1)
PUT /rest/layers/city:towns
{
    "layer": {
        "defaultStyle": {
            "name": "towns"
        },
        "enabled": true
    }
}

In code block 1.2; is application/vnd.ogc.sld+xml correct ?