Missing session_params on login with request_path

I’ve implemented PowAssent 0.4.18 and have it working for a couple of providers. The baseline functionality works - that is, I can login by clicking the login link.

When I try to access a protected resource I’m correctly redirected to the login page. But I get an error on callback

[error] Strategy failed with error: Key :session_params not found in config mfa=PowAssent.Phoenix.AuthorizationController.log_strategy_error/1

I can see the request_path making it into the AuthorizationController.

[debug] Processing with PowAssent.Phoenix.AuthorizationController.new/2
  Parameters: %{"provider" => "github", "request_path" => "/games/accept_invite/1Gdev_E_bVcOW9kW610Wh_ueZMbIIAW8bslGCE7SyFUabSrWg1eRv1SS8h0lc_Ox"}
  Pipelines: [:browser] mfa=Phoenix.Logger.phoenix_router_dispatch_start/4

but don’t see the value in the returned conn

 :pow_assent_session_params => %{
       state: "15bd28ea1e4fb57a58c87462c14bc89dab817b83e48de02e"

I get the error on OIDC as well as OAuth2 (such as Github). Ideas?