Refresh Access Tokens Gives Invalid Grant Error

Hi there,
I’m using ideas from the WordPress plugin to provide extra features to users on my MultiSite network. I can authenticate users against Patreon and when I store the access_token and refresh_token everything works as expected.

However, when I come to refresh the token, I get an ‘invalid grant’ error message. I pass in my client id and secret, and the user’s refresh token which I stored when they first connected their account. Is there anything else I should be doing?

Ta,
Steve.

Did you install & activate Patreon WordPress across entire network?

If so, did each of these sites go through the setup process by their owners to connect the site to their Patreon account?

Or do you have your own plugin which you are including code from Patreon WordPress?