AWS Scheduler: ActionAfterCompletion

I am trying to create an AWS Schedule from a lambda function. It works in general, but I am not able to set the "ActionAfterCompletion" to DELETE. For some reason, this value is not set with the following SDK Code:

import { SchedulerClient, CreateScheduleCommand, CreateScheduleCommandInput } from '@aws-sdk/client-scheduler';

export async function createSchedule(targetTime: Date, setValue: boolean) {
  const client = new SchedulerClient({ region: 'my-region' });

  const functionName = 'myFunctionName';
  const lambdaFunctionArn = `myArn:${functionName}`;

  const payload = {
    key: setValue
  };

  const scheduleName = `myScheduleName-${targetTime.getTime()}-${setValue}`;

  const scheduleParams: CreateScheduleCommandInput = {
    Name: scheduleName,
    Description: 'My description',
    ScheduleExpression: `at(${targetTime.toISOString().split('.')[0]})`,
    Target: {
      Arn: lambdaFunctionArn,
      RoleArn: 'myRoleArn',
      Input: JSON.stringify(payload),
    },

    FlexibleTimeWindow: {
      Mode: 'OFF',
    },
   ActionAfterCompletion: 'DELETE', // HERE
  };

  const createScheduleCommand = new CreateScheduleCommand(scheduleParams);

  try {
    const response = await client.send(createScheduleCommand);
    console.log('Schedule created:', response);
  } catch (err) {
    console.error('Error:', err);
  }
}

The lambda function calls this method and it works in general, but it just ignores the ActionAfterCompletion: 'DELETE'

Thank you for any help!