Azure B2C Custom Policies - Custom claim from query parameter

Question

I have an application that creates a user based on the access token received from Azure AD B2C. I am using custom policies for the sign-in, and I want to include an invite claim based on a value received from a query parameter in the azure b2clogin link.

I am using a single page application (SPA), and get my authorization token and then my access token using PKCE.

This is my SignIn.xml:

(...)
  <RelyingParty>
    <DefaultUserJourney ReferenceId="SignUpOrSignInModified" />
    <Endpoints>
      <!--points to refresh token journey when app makes refresh token request-->
      <Endpoint Id="Token" UserJourneyReferenceId="RedeemRefreshToken" />
    </Endpoints>
    <UserJourneyBehaviors>
      <JourneyInsights TelemetryEngine="ApplicationInsights" InstrumentationKey="x" DeveloperMode="true" ClientEnabled="false" ServerEnabled="true" TelemetryVersion="1.0.0" />
    </UserJourneyBehaviors>
    <TechnicalProfile Id="PolicyProfile">
      <DisplayName>PolicyProfile</DisplayName>
      <Protocol Name="OpenIdConnect" />
      <OutputClaims>
        <OutputClaim ClaimTypeReferenceId="displayName" />
        <OutputClaim ClaimTypeReferenceId="givenName" />
        <OutputClaim ClaimTypeReferenceId="surname" />
        <OutputClaim ClaimTypeReferenceId="objectId" PartnerClaimType="sub"/>
        <OutputClaim ClaimTypeReferenceId="tenantId" AlwaysUseDefaultValue="true" DefaultValue="{Policy:TenantObjectId}" />
      </OutputClaims>
      <SubjectNamingInfo ClaimType="sub" />
    </TechnicalProfile>
  </RelyingParty>
</TrustFrameworkPolicy>

This is my TrustFrameworkExtensions.xml:

(...)
  <BuildingBlocks>
    <ContentDefinitions>
      <ContentDefinition Id="api.localaccountsignup">
        <DataUri>urn:com:microsoft:aad:b2c:elements:contract:unifiedssp:1.2.0</DataUri>
      </ContentDefinition>
    </ContentDefinitions>
  </BuildingBlocks>

  
  <ClaimsProviders>
    <ClaimsProvider>
      <DisplayName>Local Account</DisplayName>
      <TechnicalProfiles>
        <TechnicalProfile Id="SelfAsserted-LocalAccountSignin-Email">
          <Metadata>
            <Item Key="setting.showSignupLink">false</Item>
          </Metadata>
        </TechnicalProfile>
      </TechnicalProfiles>
    </ClaimsProvider>


    <ClaimsProvider>
      <DisplayName>Local Account SignIn</DisplayName>
      <TechnicalProfiles>
         <TechnicalProfile Id="login-NonInteractive">
          <Metadata>
            <Item Key="client_id">x</Item>
            <Item Key="IdTokenAudience">x</Item>
          </Metadata>
          <InputClaims>
            <InputClaim ClaimTypeReferenceId="client_id" DefaultValue="x" />
            <InputClaim ClaimTypeReferenceId="resource_id" PartnerClaimType="resource" DefaultValue="x" />
          </InputClaims>
        </TechnicalProfile>
      </TechnicalProfiles>
    </ClaimsProvider>

  </ClaimsProviders>


  <UserJourneys>

    <UserJourney Id="SignUpOrSignInModified">
      <OrchestrationSteps>

        <OrchestrationStep Order="1" Type="CombinedSignInAndSignUp" ContentDefinitionReferenceId="api.signuporsignin">
          <ClaimsProviderSelections>
            <ClaimsProviderSelection ValidationClaimsExchangeId="LocalAccountSigninEmailExchange" />
          </ClaimsProviderSelections>
          <ClaimsExchanges>
            <ClaimsExchange Id="LocalAccountSigninEmailExchange" TechnicalProfileReferenceId="SelfAsserted-LocalAccountSignin-Email" />
          </ClaimsExchanges>
        </OrchestrationStep>

        <OrchestrationStep Order="2" Type="ClaimsExchange">
          <ClaimsExchanges>
            <ClaimsExchange Id="getinvorchstep" TechnicalProfileReferenceId="getinv" />
          </ClaimsExchanges>
        </OrchestrationStep>

        <!-- This step reads any user attributes that we may not have received when in the token. -->
        <OrchestrationStep Order="3" Type="ClaimsExchange">
          <ClaimsExchanges>
            <ClaimsExchange Id="AADUserReadWithObjectId" TechnicalProfileReferenceId="AAD-UserReadUsingObjectIdModified" />
          </ClaimsExchanges>
        </OrchestrationStep>

        <OrchestrationStep Order="4" Type="SendClaims" CpimIssuerTechnicalProfileReferenceId="JwtIssuer" />

      </OrchestrationSteps>
      <ClientDefinition ReferenceId="DefaultWeb" />
    </UserJourney>
  </UserJourneys>


</TrustFrameworkPolicy>

I have tried a bunch of things, but I had most hope for doing something like this page recommends at the top

However, when I do that I get this returned when I call https://tenant-name.b2clogin.com/tenant-name.onmicrosoft.com/B2C_1A_signin/oauth2/v2.0/token:

{
    "error": "invalid_grant",
    "error_description": "AADB2C90085: The service has encountered an internal error. Please reauthenticate and try again.\r\nCorrelation ID: c56b5973-875c-4329-9867-cdc7937484cf\r\nTimestamp: 2023-08-22 10:02:56Z\r\n"
}