Concourse stop getting a resource



I need some help to understand what is happening with our Concourse installation. We have Concourse working in an AWS EC2 Ubuntu instance (web and worker). Some of the resources we need are in an AWS S3 bucket and suddenly, one of these resources cannot be gotten (no error message is shown). We have other resources in the same bucket with no issue.

The resource is a file called ‘keystore.jks’ and I’ve noticed that If I change the name of the file I can get the resource.
I’ve tried ‘check-resource’ and I get a 504 error.

What could be happening??

We are using Concourse v4.0.0