Amazon Managed Grafana - Google Workspace SAML SSO - "corresponding relay state is not found: https..."

We are using Amazon Managed Grafana with Google Workspace SAML SSO.

When using the Sign in with SAML login button directly from the Grafana /login route on the AWS provided domain, access is successfully permitted.

However, when trying to use IdP-initiated sign-on from Google Workspace Google apps, we receive the following error message:

corresponding relay state is not found: https://<name>.grafana-workspace.<region>.amazonaws.com/login/saml

Within the SAML/SSO configuration in Google Workspace, we have provided the Start URL value as https://<name>.grafana-workspace.<region>.amazonaws.com/login/saml. Additionally, we not selected the Signed response option.

Any thoughts?