Adding claims to access token received from B2C custom policy - azure-ad-b2c

Question

I have a problem where I need the access token received from a custom policy B2C flow to contain certain claims, for example email. I have one flow for local login (email + password) and that gives me a correct access token, it contains email. However, my other flow for social IDP does not give an access token with any extra claims. An access token from Facebook looks something like this:
{
"typ": "JWT",
"alg": "RS256",
"kid": "IiippFxxxxxxxxxxxxxxxxxxqVEz16tNMOR0"
}.{
"iss": "https://xxxxxxxxxxxxxxx.b2clogin.com/a861612f-xxxxxxxxxxxxxxxx-34e14528d/v2.0/",
"exp": 1671466114,
"nbf": 1671462514,
"aud": "b0823952xxxxxxxxxxxxxxxx363b7bdfe0a",
"sub": "c1aceafd-xxxxxxxxxxxxxxxf4f1a0a83a7",
"idp": "facebook.com",
"tid": "a861612fxxxxxxxxxxxxxxxxxxxce534e14528d",
"nonce": "73eee291-xxxxxxxxxxxxxf6-85818e3efdab",
"scp": "user.read",
"azp": "b0823952-xxxxxxxxxxxxxxx2363b7bdfe0a",
"ver": "1.0",
"iat": 1671462514
}.[Signature]
While the access token from a local sign in looks like this:
{
"typ": "JWT",
"alg": "RS256",
"kid": "IiippFPBuNxxxxxxxxxxxxxxxxxxxPDWO9qVEz16tNMOR0"
}.{
"iss": "https://xxxxxxxxxxxxxxxx.b2clogin.com/a861612f-xxxxxxxxxxxxxxxxx14528d/v2.0/",
"exp": 1671546543,
"nbf": 1671542943,
"aud": "b0823952xxxxxxxxxxxxxxxx363b7bdfe0a",
"sub": "c1aceafd-xxxxxxxxxxxxxxxx1f4f1a0a83a7",
"userIdentities": [
{
"issuer": "https://oidc.test.xxxxx.com",
"issuerUserId": "1xxxxxxxxxxxxx9"
},
{
"issuer": "linkedin.com",
"issuerUserId": "xxxxxxxxxx"
},
{
"issuer": "facebook.com",
"issuerUserId": "xxxxxxxxxxxxx"
}
],
"email": "my#email.com",
"name": "My name",
"given_name": "My",
"family_name": "Name",
"idp": "Local",
"tid": "a86161xxxxxxxxxxxxxxxxxxxx4e14528d",
"nonce": "e080be59xxxxxxxxxxxxxxxxxxxx5bfa353bd601",
"scp": "user.read",
"azp": "b0823952xxxxxxxxxxxxx3b7bdfe0a",
"ver": "1.0",
"iat": 1671542943
}.[Signature]
I know that there's several kinds of tokens and it is the access token I need, not ID token or refresh token. The access token from the custom policy flow will be automatically injected into my API calls by MSAL interceptor in the frontend.
None of my specified OutputClaims in my Custom policy are present in the access token. I have also tried adding optionalClaims in my applications manifest in Azure portal like this:
"optionalClaims": {
"idToken": [],
"accessToken": [
{
"name": "email",
"source": "user",
"essential": true,
"additionalProperties": []
}
],
"saml2Token": []
},
I've also tried mail instead of email, and User instead of user.