Unable to generate access_token keep getting "invalid_grant" error

Hi All,

I am trying to connect lightspeed using OAuth2.0 process. I am able to generate temporary authorization code but POST to generate the token fails with response:

"error": "invalid_grant",

"error_description": "Authorization code doesn't exist or is invalid for the client"

When I try redirect_uri on my Add-on as "https://webhook.site/..." and that works perfectly fine. I am able to generate the access_token and refresh_token.

Has anyone else faced the same issue? how did you go about resolving it?