403: Forbidden We need an email address or a handle from your login service.

Error message: 403: Forbidden We need an email address or a handle from your login service. To use this login, please update your account with the missing info. Learn more.
...when logging in.

Steps to reproduce the behavior:
* Set up SWA using React with plan "Standard", use Python functions for backend
* Set up B2C directory
* Use "web" and not SPA as type of application for the app registration
* Use local account with IDP "email" as identity provider
* Use user flows for defining the signup/login procedure
identity provider: email signup
user attributes: user name, email address
application claims: identity provider, email addresses
* Add "B2C_CLIENT_ID" and "B2C_CLIENT_SECRET" to configuration of SWA

staticwebapp.config.json

```
{
"routes": [
{
"route": "/login",
"allowedRoles": ["anonymous"],
"rewrite": "/.auth/login/b2c"
},
{
"route": "/logout",
"allowedRoles": ["authenticated"],
"rewrite": "/.auth/logout"
},
{
"route": "/.auth/login/aad",
"allowedRoles": ["anonymous", "authenticated"],
"statusCode": 404
},
{
"route": "/.auth/login/apple",
"allowedRoles": ["anonymous", "authenticated"],
"statusCode": 404
},
{
"route": "/.auth/login/b2c",
"allowedRoles": ["anonymous"]
},
{
"route": "/.auth/login/facebook",
"allowedRoles": ["anonymous", "authenticated"],
"statusCode": 404
},
{
"route": "/.auth/login/github",
"allowedRoles": ["anonymous", "authenticated"],
"statusCode": 404
},
{
"route": "/.auth/login/google",
"allowedRoles": ["anonyous", "authenticated"],
"statusCode": 404
},
{
"route": "/.auth/login/twitter",
"allowedRoles": ["anonymous", "authenticated"],
"statusCode": 404
},
{
"route": "/*",
"allowedRoles": ["authenticated"]
}
],
"navigationFallback": {
"rewrite": "/index.html",
"exclude": [
"/css/*",
"/img/*",
"/js/*"
]
},
"responseOverrides": {
"401": {
"statusCode": 302,
"redirect": "/login"
}
},
"auth": {
"identityProviders": {
"customOpenIdConnectProviders": {
"b2c": {
"registration": {
"clientIdSettingName": "B2C_CLIENT_ID",
"clientCredential": {
"clientSecretSettingName": "B2C_CLIENT_SECRET"
},
"openIdConnectConfiguration": {
"wellKnownOpenIdConfiguration": "https://lw.b2clogin.com/lw.onmicrosoft.com/B2C_1_lw_flow/v2.0/.well-known/openid-configuration"
}
},
"login": {
"nameClaimType": "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/name",
"scopes": [],
"loginParameterNames": []
}
}
}
}
}
}
```

**Expected behavior**
User is logged in

**Device info (if applicable):**
MacOS, same error on all browsers tested (Chrome, Firefox, Safari)

The problem is mentioned in issue #413 but solution of @mkarmark is not applicable for my case. Running the user flow in the portal also produces the same error message