WordPress configuration causing plugin page to return 403 http status

I’ve set up a bitnami powered wordpress server on AWS and migrated an existing wordpress site to the new instance.

When accessing plugins through the wordpress admin, I encounter the message “Sorry, you are not allowed to access this page.” and the server returns a 403 http code.

An example of the URL that I see the error on is: https://stg.mydomain.com/wp-admin/admin.php?page=instapage_dashboard

When accessing the plugin pages through my ec2 public DNS domain there is no issue.

I am proxying to the ec2 domain from the mydomain server with nginx:

location /wp-admin {
rewrite ^/wp-admin/(.*)$ /$1 break;
resolver 8.8.8.8;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header Host $host;
proxy_pass http://ec2-ipaddress.compute-1.amazonaws.com$request_uri$is_args$args;
proxy_redirect off;
}
On the ec2 server I am running apache rather than nginx. Is there some kind of cookie or header I might not have access to in the wordpress admin when accessing from mydomain rather than the ec2 domain?