Enterprise SAML IdP initiated Auth0 resume issues GET on callback instead of POST

I’m implementing my first enterprise SAML connection in addition to an existing and functioning database connection. The app uses OIDC with Auth0 and has worked fine on the database connection for a few months.

When using an IdP-initiated session over the enterprise connection, the users are created in Auth0 fine, but on the final redirect by auth0/resume to my application callback URL, we inexplicably receive a GET request instead of a POST request as per the Sp-initiated DB connection OIDC flow.

I’m not expecting to handle this in my OIDC client code in the application and throw the obvious method error.

QUESTION: Is this method an issue I should try to code around in my app, a config error or an auth0 bug?