Issues with Refresh Token Handling in OAuth 2.0

Hi
I have a similar problem and I hope you might be able to help.

I have a custom connector that works. It authenticates to Auth0 and gets a token that expires in 24 hours. The refresh token method also works and the expired token is refreshed.

My problem is that the "refresh_token" itself expires after 7 days and even though my Auth0 is set up to rotate refresh tokens, something is not working there. The refresh token expires and I have to do a manual refresh (re-sign-in to generate a new token) before 7 days in order for the next 7 days of refreshing kicks in.

So, my question is this: what do I need to do to get the rotated refresh token to be used? 
The bit about all this that puzzles me is that even though the refresh token rotation is enabled on Auth0, I guess it is not really rotating the refresh token because, if it was, the second attempt to refresh using the old refresh token would fail.

At any rate, the symptoms of what is happening seems to indicate that the refresh token is not rotating and the old refresh token is reused until it expires (in 7 days in my case)
Here is my code if it helps any:

StartLogin = (dataSourcePath, state, display) =>
    let
        json = Json.Document(dataSourcePath),
        codeVerifier = Text.NewGuid() & Text.NewGuid(),
        codeChallenge = Base64UrlEncodeWithoutPadding(Crypto.CreateHash(CryptoAlgorithm.SHA256, Text.ToBinary(codeVerifier, TextEncoding.Ascii))),

        AuthorizeUrl = json[auth_url] & "?" & Uri.BuildQueryString([
            client_id = json[client_id],
            state = state,
            redirect_uri = redirect_uri,
            scope = DataMosaixDefaults[Scope],//json[scope],
            audience = DataMosaixDefaults[Audience],//json[audience],
            code_challenge_method = "S256",
            code_challenge = codeChallenge,
            response_type = "code"])
    in
        [
            LoginUri = AuthorizeUrl,
            CallbackUri = redirect_uri,
            WindowHeight = windowHeight,
            WindowWidth = windowWidth,
            Context = [code_verifier = codeVerifier]
        ];

FinishLogin = (clientApplication, dataSourcePath, context, callbackUri, state) =>
    let
        json = Json.Document(dataSourcePath),
        Parts = Uri.Parts(callbackUri)[Query]
    in
        TokenMethod("authorization_code", json[deployment], Parts[code], json[token_url], json[client_id], context);

Refresh = (dataSourcePath, refreshToken, oldCredential) =>
    let
        json = Json.Document(dataSourcePath),
        refreshToken = oldCredential[refresh_token],
        result = TokenMethod("refresh_token", json[deployment], refreshToken, json[token_url], json[client_id])
    in
        result;

TokenMethod = (grant_type, deployment, authCode, token_url, client_id, optional context) =>
    let
        CodeVerifier = if (context <> null) then [code_verifier = context[code_verifier]] else [],
        Parameters = if (grant_type = "authorization_code") then [ redirect_uri = redirect_uri, code = authCode ] else [ refresh_token = authCode ],
        Response = Web.Contents(token_url, [
            Content = Text.ToBinary(Uri.BuildQueryString([
                client_id = client_id,
                grant_type = grant_type,
                redirect_uri = redirect_uri] & Parameters & CodeVerifier)),
            Headers=[#"Content-type" = "application/x-www-form-urlencoded",#"Accept" = "application/json"]]),
        RefreshToken = if (grant_type = "authorization_code") then [] else [ refresh_token = authCode ],
        Parts = Json.Document(Response)
    in
        Parts;