Validate Email through DisplayControl - azure-ad-b2c

Question

Our current reset password flow works by first showing you a field for email address. Then sends you an email with OTP code to verify your email with and goes on with a password reset. We use the starter pack and SendGrid for the emails, implemented with Microsoft's example documentation for it.
I cannot get the custom policy to verify/validate that the email actually exists as a registered user (i.e. has objectId) in our AAD prior to sending the email.
What I want is: the policy checks if this email address is already registered on AAD. If yes, then it proceeds and sends a OTP code to verify the email, helps the user to reset the password. If not, interrupt the flow, do not send any email and do not return any error message.
Microsoft has a working demo of this, but for sign in.
This is the UserJourney for Password Reset that I use:
<UserJourney Id="PasswordReset">
<OrchestrationSteps>
<OrchestrationStep Order="1" Type="ClaimsExchange">
<ClaimsExchanges>
<ClaimsExchange Id="PasswordResetUsingEmailAddressExchange" TechnicalProfileReferenceId="LocalAccountDiscoveryUsingEmailAddress" />
</ClaimsExchanges>
</OrchestrationStep>
<OrchestrationStep Order="2" Type="ClaimsExchange">
<ClaimsExchanges>
<ClaimsExchange Id="NewCredentials" TechnicalProfileReferenceId="LocalAccountWritePasswordUsingObjectId" />
</ClaimsExchanges>
</OrchestrationStep>
<!-- Send security alert email -->
<OrchestrationStep Order="3" Type="ClaimsExchange">
<ClaimsExchanges>
<ClaimsExchange Id="Sendalertemail" TechnicalProfileReferenceId="Alertemail" />
</ClaimsExchanges>
</OrchestrationStep>
<OrchestrationStep Order="4" Type="SendClaims" CpimIssuerTechnicalProfileReferenceId="JwtIssuer" />
</OrchestrationSteps>
<ClientDefinition ReferenceId="DefaultWeb" />
</UserJourney>
The contents of the technical profile in step 1:
<TechnicalProfile Id="LocalAccountDiscoveryUsingEmailAddress">
<DisplayName>Reset password using email address</DisplayName>
<Protocol Name="Proprietary" Handler="Web.TPEngine.Providers.SelfAssertedAttributeProvider, Web.TPEngine, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
<Metadata>
<Item Key="IpAddressClaimReferenceId">IpAddress</Item>
<Item Key="ContentDefinitionReferenceId">api.localaccountpasswordreset</Item>
</Metadata>
<IncludeInSso>false</IncludeInSso>
<DisplayClaims>
<DisplayClaim DisplayControlReferenceId="emailVerificationControl" />
</DisplayClaims>
<OutputClaims>
<OutputClaim ClaimTypeReferenceId="email" />
<OutputClaim ClaimTypeReferenceId="objectId" />
<OutputClaim ClaimTypeReferenceId="userPrincipalName" />
<OutputClaim ClaimTypeReferenceId="authenticationSource" />
</OutputClaims>
<ValidationTechnicalProfiles>
<ValidationTechnicalProfile ReferenceId="AAD-UserReadUsingEmailAddress-emailAddress" />
</ValidationTechnicalProfiles>
</TechnicalProfile>
And the validation technical profile from it:
<TechnicalProfile Id="AAD-UserReadUsingEmailAddress-emailAddress">
<Metadata>
<Item Key="Operation">Read</Item>
<Item Key="RaiseErrorIfClaimsPrincipalDoesNotExist">true</Item>
</Metadata>
<IncludeInSso>false</IncludeInSso>
<InputClaims>
<InputClaim ClaimTypeReferenceId="email" PartnerClaimType="signInNames.emailAddress" Required="true" />
</InputClaims>
<OutputClaims>
<!-- Required claims -->
<OutputClaim ClaimTypeReferenceId="objectId" />
<OutputClaim ClaimTypeReferenceId="authenticationSource" DefaultValue="localAccountAuthentication" />
<!-- Optional claims -->
<OutputClaim ClaimTypeReferenceId="userPrincipalName" />
<OutputClaim ClaimTypeReferenceId="displayName" />
<OutputClaim ClaimTypeReferenceId="otherMails" />
<OutputClaim ClaimTypeReferenceId="signInNames.emailAddress" />
</OutputClaims>
<IncludeTechnicalProfile ReferenceId="AAD-Common" />
</TechnicalProfile>
I tried this solution, but it didn't change the behavior of my page at all.

Answer 1

I managed to solve this by adding this to the SendCode action, before GenerateOtp:
<ValidationClaimsExchangeTechnicalProfile TechnicalProfileReferenceId="AAD-UserReadUsingEmailAddress-emailAddress" ContinueOnError="false" />
AAD-UserReadUsingEmailAddress-emailAddress is responsible for checking for objectId against AAD.
Then, a precondition, within SendOtp:
<Precondition Type="ClaimsExist" ExecuteActionsIf="false">
<Value>objectId</Value>
<Action>SkipThisValidationTechnicalProfile</Action>
</Precondition>