Automation account runbook jobschedules

[anderssonpof]

I'm trying to link runbooks with jobschedules in my automation account and I'm getting a nonsensical error.

var config = loadJsonContent('params.json')

resource automationAccount 'Microsoft.Automation/automationAccounts@2023-11-01' existing = {
  name: 'automationAccountName'
}

module jobSchedule '../../../modules/automation/jobSchedule.bicep' = [for item in config.jobschedules: {
  name: toUpper('jobSchedules-${take(replace(item.runbookName, '_', '-'), 35)}')
  params: {
    automationAccountName: automationAccount.name
    parameters: item.parameters
    runbookName: item.runbookName
    hybridWorkerGroupName: item.hybridWorkerGroupName
    scheduleName: item.scheduleName
  }
}]

The module

param automationAccountName string
@description('If you have parameters for your script, defaults to empty')
param parameters object = {}
param runbookName string
@description('Which worker group should this schedule run on')
param hybridWorkerGroupName string
param scheduleName string

var name = guid(runbookName, automationAccountName, scheduleName)

resource automationAccount 'Microsoft.Automation/automationAccounts@2023-11-01' existing = {
  name: automationAccountName
}

resource schedule 'Microsoft.Automation/automationAccounts/schedules@2023-11-01' existing = {
  name: scheduleName
}

resource runbook 'Microsoft.Automation/automationAccounts/runbooks@2023-11-01' existing = {
  name: runbookName
}

resource hybridWorkerGroup 'Microsoft.Automation/automationAccounts/hybridRunbookWorkerGroups@2023-11-01' existing = {
  name: hybridWorkerGroupName
}

resource jobSchedule 'Microsoft.Automation/automationAccounts/jobSchedules@2023-11-01' = {
  name: name
  parent: automationAccount
  properties: {
    parameters: parameters
    runbook: {
      name: runbook.name
    }
    runOn: hybridWorkerGroup.name
    schedule: {
      name: schedule.name
    }
  }
}

params.json

{
"jobschedules": [
        {
            "parameters": {
                "hostnames": [
                    "example.org",
                    "example.com",
                ],
                "kv": "\"kv\""
            },
            "runbookName": "runbookName",
            "hybridWorkerGroupName": "HybridGroupProd",
            "scheduleName": "Weekly"
        }
    ]
}

I'm getting this from ARM

{
  "code": "BadRequest",
  "message": "{\"Message\":\"Model cannot be null.\"}"
}

There is no model in https://learn.microsoft.com/en-us/azure/templates/microsoft.automation/automationaccounts/jobschedules?pivots=deployment-language-bicep
or
https://learn.microsoft.com/en-us/rest/api/automation/job-schedule/create?view=rest-automation-2023-11-01&tabs=HTTP