Thank you for posting your query on re:Post. As I understand, you are facing issue configuring the Nginx proxy, however the changes are not copying to the desired location.
As per the directory structure is concerned, the one you mentioned seems correct to me. Based on the documentation, the .platform directory should be at the root of the source bundle.
 Extending Elastic Beanstalk Linux platforms - https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/platforms-linux-extend.html
Now, since this is working on other applications, there is something specific to your current application which is causing the issue. Therefore, is it possible for you reach out to AWS Support via the support case (for privacy concerns) for further troubleshooting on the issue.
Please share the complete bundle logs, details of the environment like environment name or id. for more insights.
Further on the copy command, the command is executed after the nginx configuration is validated. Please refer the below logs for my replication.
2022/09/12 14:32:07.721209 [INFO] Executing instruction: start proxy with new configuration
2022/09/12 14:32:07.721232 [INFO] Running command /bin/sh -c /usr/sbin/nginx -t -c /var/proxy/staging/nginx/nginx.conf
2022/09/12 14:32:07.731058 [INFO] nginx: the configuration file /var/proxy/staging/nginx/nginx.conf syntax is ok
nginx: configuration file /var/proxy/staging/nginx/nginx.conf test is successful
2022/09/12 14:32:07.731356 [INFO] Running command /bin/sh -c cp -rp /var/proxy/staging/nginx/* /etc/nginx
Therefore, can you please check if in the logs you are getting anything apart from the log entry you mentioned.
Hoping that the above helps. Thank you.
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