Redshift jdbc using ping federation

Question

I've set up idp ping and redshift according to the instructions on https://aws.amazon.com/blogs/big-data/federating-single-sign-on-access-to-your-amazon-redshift-cluster-with-pingidentity/, but on trying to connect get

com.amazon.redshift.Driver.connect: com.amazonaws.SdkClientException: SAML error: Invalid base64 SAMLResponse (Service: AWSOpenIdDiscoveryService; Status Code: 400; Error Code: AuthSamlInvalidSamlResponseException; Request ID: b3c22382-c3cd-4a5f-8f1c-b8e7fa2cb948; Proxy: null) (Service: AWSSecurityTokenService; Status Code: 400; Error Code: InvalidIdentityToken; Request ID: 5e5080db-f5d6-4fb5-b1f9-0ca9a6ea3ec4; Proxy: null)

I've set debug on the driver and response can be decoded to the expected saml response attributes.

I did get this working a few months ago but it seems to no longer work

Any help or indication that others have this working gratefully received.