AWS CLI & Cognito : Able to list user details but unable to list all users

Hi,

Using the following CLI command I can list the details of a particular user :

aws cognito-idp admin-get-user --user-pool-id eu-west-1_a3LWXXXXX --username user.test1

However, if I try and list all the users from that pool using the following command :

aws --region us-west-1 cognito-idp list-users --user-pool-id eu-west-1_a3LWXXXXX --limit 60

I get the following error:

An error occurred (ResourceNotFoundException) when calling the ListUsers operation: User pool eu-west-1_a3LWXXXXX does not exist.

Can anyone please advise?

Many many thanks