For AWS accounts accessed via CrossAccount Sign in, and all therefore using the same access key id and secret access key, when specifying the Account Type as Amazone S3(Credentials from AWS config or credential file), and config is specified, and the config file contains (an example entry):-

[default]
aws_access_key_id = AKI****************A
aws_secret_access_key = iqI3********************************KHF+
output = json
region = eu-west-1

[profile TangentPlc]
role_arn = arn:aws:iam::817172743388:role/CrossAccountAdmin
source_profile = default
output = json
region = eu-west-1

The command
aws --profile TangentPlc s3 ls
list the bucket names in that account

however s3browser lists the buckets in the default account.