@cafrida – since its mentioned as AWS wordpress image, assuming its a docker image. I am not an expert in AWS terminologies.
We have faced the similar issue; In local react application was rendered perfectly, but same app when its deployed in docker wordpress image react-app section was not showing.
In docker image or machine, check the hosts entry ( /etc/hosts) and see where the hosted domain is pointing. From the machine, if PHP is not able to resolve https://domain.com/wp-content/reactpress/apps/yourappname/build/assets-manifest.json it won’t be able to attach the react app into the content page.
When the reactpress tries to read the asset-manifest.json over the internet using @file_get_contents function for injecting the scripts and css, it may be failing in doing so, this results in not showing the react app.
The entire logic happening in repr_load_react_app() function under plugins folder ( /wp-content/plugins/reactpress/public/class-reactpress-public.php )