Jira agile endpoint for oauth

Hello Atlassian Dev Community,
I was using simple atlassian token based authentication for getting data and it was working for both rest/api endpoint as well as rest/agile endpoint. I recently started to shift to OAuth 2.0 (3LO) to make it easy for me to make my application available for other users, but access token I received in the process is not working on rest/agile endpoint. On trying to access agile endpoint for getting board sprint data I am getting 403 Client Error: Forbidden for URL.
could there be someting wrong with oauth scope or is it not available for agile endpoint yet?

@AshishVats,

Can you be more specific about the endpoints & URLs you are constructing? Which mechanism are you using for obtaining the cloudId of your site?

@ibuchanan
I followed the steps on https://developer.atlassian.com/cloud/jira/platform/oauth-2-3lo-apps/#enabling-oauth-2-0–3lo- to implement oauth 2.0 (3LO) using pyton. I first received the code on callback endpoint when the user accepted authorize app, using the code I got access token and then cloudid from https://api.atlassian.com/oauth/token/accessible-resources .
This acces code and cloud id is working for rest api endpoints but when I tried /rest/agile/1.0/board/{boardId}/sprint endpoint, it gave above mentioned error.