Inconsistent behavior on Management API - get KVM Map

I am trying to retrieve the entries of this key value map by calling the management API:

[https://api.enterprise.apigee.com/v1/organizations/{org}/environments/prod/keyvaluemaps/app-storage-service](https://api.enterprise.apigee.com/v1/organizations/{org}/environments/prod/keyvaluemaps/app-storage-service)

but once in a while I get status coded 404 and after retrying couple of times I get 200

why is this behaviour happening and how can I be sure that the value really exists or absent?