EventBridge Scheduler - Only one out of 4 functions work.

Hello.

Are there any errors in CloudWatch Logs?
Is it possible for you to share the Lambda code as well?

Also, if you only want to stop and start EC2, I think it would be easier to set up Amazon EventBridge Scheduler without creating Lambda.
The blog below configures Amazon EventBridge Scheduler to stop EC2, but you can configure the settings for starting it using almost the same steps.
https://dev.to/aws-builders/easy-setup-for-ec2-stop-jobs-with-amazon-eventbridge-scheduler-4lpg

There's no errors, for one of the functions it has the log of when the server was stopped. But for everything theres no logs at all, only for when a test has been ran.

Start Instance (Removed instance ID)

import boto3
region = 'eu-west-2'
instances = [''] 

ec2 = boto3.client('ec2', region_name=region)

def lambda_handler(event, context):
    ec2.start_instances(InstanceIds=instances)
    print('started your instances: ' + str(instances))

Stop Instance

import boto3
region = 'eu-west-2'
instances = ['']

ec2 = boto3.client('ec2', region_name=region)

def lambda_handler(event, context):
    ec2.stop_instances(InstanceIds=instances)
    print('stopped your instances: ' + str(instances))

I could try use the method you've posted.